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SCIENCETeacher Instruction Manual
Chemistry & Physics
Grade 102007
Department of Science, Health & Physical EducationFaculty of Science &Technology
National Institute of Education
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Science
Grade 10Chemistry & Physics2007
© National Institute of Education
ISBN-
Department of Science, Health & Physical Education,Faculty of Science &Technology,National Institute of Education.
Printing:NIE Press,National Institute of Education,Maharagama.
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Message of the Director General
The first curriculum revision for the new millennium is based on the elimination of the severalproblems obtaining in the present education system. The present curriculum reforms have beenplanned having identified the problems that youth face consequent to the weakening of theirthinking abilities, social abilities as well as personal abilities and step by step exploration offactors leading to this situation, to overcome which, the necessary background was prepared.
Compared to the other countries in the Asian region, our country took the lead in education inearlier years. But most countries in this region have superceded Sri Lanka in education today.Some factors that influenced this deterioration are the action taken by educational institutions tocontinue to take action to confirm the known, learn that which had been decided on earlier, andreconstruct that which was, in the same form itself.
All these matters have been taken into consideration and the officers of the National Institute ofEducation have endeavoured to prepare the new curriculum on the basis of a distinct philosophy.The primary objective here is to change that which is known, explore that which is new anddevelop that which is necessary for tomorrow and build up a generation of students who candisplay their readiness for a successful future. But there is no need to reiterate, the need for avisible change in the teacher’s role for the realization of this objective. In place of the obvioustransactional teacher role presenting in our classrooms so far, the Sri Lankan school teacher willhave to understand and conform to a student-centered, competency based and activity focusedtransformational role.
It is our firm belief that this Teacher Instruction Manual will serve you as an aid to become aneffective teacher through the provision of numerous instructions that will help you adapt to thenew situation. Through the study of these instructions you will be provided the opportunity ofmaking your daily teaching as well as the evaluation task easy. There is no doubt that instructionsfor student exploration and other quality inputs will help facilitate the teacher’s task. Similarly,the Teacher Instruction Manual will help convey to school principals valuable information theycan use in time-tabling, sharing of limited resources and internal supervision.
My sincere thanks go to Dr. Mrs. I. L. Ginige, Assistant Director General (CurriculumDevelopment) Science & Technology Faculty of National Institute of Education for her directinvolvement in the preparation of this Teacher Instruction Manual that will serve an immensepurpose in the task performed at school level by the section above and also teacher educationistinvolved in beginning or continuous teacher educational matters, in-service advisors as well asofficers at various levels, involved in external supervision plus monitoring programmes.
Professor J. W. WickramasingheDirector GeneralNational Institute of Education
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PrefaceThe first curriculum reform for the millennium implemented with the aim of preparing a
powerful basis for a new Sri Lanka anticipates a visible transformation of the teacher’s role. Thethree main sections below are included in the Teacher Instruction Manual prepared with theobjective of providing the teacher with the necessary support in this regard.
· Detailed Syllabus· Activity Continuum that helps in the implementation of the syllabus· Instruments for the extension of the learning teaching process.Teachers have been provided the opportunity of understanding several basic matters that
have been taken into consideration in the preparation of the curriculum for the detailed syllabusextending beyond subject topics and sub-topics. Competency levels that correspond to subjectcompetency have been included in this section that commences with an introduction to the factorsand subject aims that formed the basis of the new syllabus. One special features of this section isthat, while the knowledge-base determined under competency level each student needs to develophas been introduced as the subject content the multiple learning and teaching methods employedin transmitting this section to the student has also been taken into consideration in determining thetime frame with respect to each competency level.The final part of the detailed syllabus presented under the heading “School Policy and Programs”needs to be studied very carefully and understood by every instructional leader. This sectionprovides school managers a range of valuable instructions to assist them in the allocation forteaching, subject-teaching assigning functions to teachers, implementing co-curricular activitiesas well as supervision of the teacher’s task. The second section of the Teacher Instruction Manualhas been prepared with the objective of providing teachers with clear understanding of the proposedlearning- teaching methodology. This section commences with the introduction of the methods ofplanning activities under competency-based education as well as the change in the teacher’s role.Although the activity continuum necessary for the implementation of the curriculum has beenintroduced next, the implementation of the proposed activity in the very same manner is notexpected of teachers. The teacher should endeavor to make use of his / her creative, as well ascritical thinking abilities and adapt these activities in a manner that suits ones class, best. Althoughinstructions have been provided on the constitution of groups in keeping with the facets of theproblems subject to exploration, the teacher is expected to take an intelligent decision on thenumber of groups based on number of students in the class.
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Time has been allocated for activities to ensure achievement of the relevant competency levels.Therefore, teachers may have to exceed the 40-minute period. While each activity has beenprovided adequate time for the actualization of each competency level, the teacher is expectedto make use of single or double periods in the time table and breakdown these activities, assuitable in implementing them.For the success of the procedure it is essential that every time an activity commenced the previousday is carried over to the following day, that a brief summary of the part of the activity completedthe previous day is presented to the class. Similarly, this decision will provide the school communitywith the opportunity of involving students in effective learning where teachers obtain leave ofabsence.The final item in this section is a list of quality inputs necessary for the maintenance of the qualityof subject learning and teaching, when taken as a whole. As such, the teacher has a choice ofordering out the necessary learning-teaching materials in time and having them on hard.
Included in the third part of the teacher Instruction Manual under the title“ Assessment and evaluation” are a number of important hints to ensure that the expected resultsof the exercise are realized.
This section has been so structured as to introduce matters related to the assessment and evaluationthat should take place under each activity, extension of the learning and teaching that takes placebased on activity groups and the nature of the questions that might be expected in generalexaminations. It must be pointed out that the primary responsibility of the teachers is to Identifyinstances where assessment and evaluation can be implemented in the course of each activityand to carry out this task successfully on the basis of common criteria. The set of instrumentsprepared with a range of activities as the objective for the purpose of extending learning andteaching provide students with the opportunity of involvement in continuous learning outside therecommended classroom sessions. While it is the task of the teacher to regularly examine thelearning students receive, based on these instruments, and encourage them, arriving at a correctdecision regarding the final results of the activities and communicating that decision to the relevantparties is expected of the teacher. It is essential that a visible change takes place in generalexaminations for the success of the learning-teaching process. The National Institute of Education,with the assistance of the Sri-Lanka Department of Examinations, has introduced several prototypequestions for educational levels that terminate with these examinations. Since this change inexamination question papers has been suggested in order to direct students to learn throughpractice and experience, instead of resorting to mechanical approaches like memorizing oranswering model question papers, the education of school students and parents about this changeshould commence at the beginning itself.
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All teachers should realize that various activities can be developed for the achievement of anyparticular competency level. Accordingly, they should be prepared for more successful teachingthrough the use of better approaches, exploration, as well as instruments for the extension oflearning and teaching.The present Teacher Instruction Manual will give teachers right throughout the country the courageto effect a visible change in the teacher’s role and prevent their becoming inactive in the presenceof new approaches. Similarly, we expect to award certificates and provide numerous developmentopportunities to teachers who go beyond the activities to involve themselves in the innovation ofnovel creations. What teachers have to do order in to become eligible to the awards is to improvethese activities, using their creative thinking, and present them. Learning-teaching plans preparedin this manner outside the basic activity plan, should be forwarded to Assistant Director General( Curriculum Development ), Science and Technology faculty, National Institute of Education,Sri Lanka. Selection of those entitled to awards will be made subsequent to the study of theseactivities by the relevant subject committees.We have endeavoured in this manner, to bring learning-teaching assessment and evaluation on tothe same platform through new methodologies. According to this, teachers will be providedsubstantial latitude to meaningfully handle the learning-teaching process, school-based assessment,as well as assignment of home-work. It is our firm conviction that the school system of Sri Lankawill, make maximum use of this aid and depart from orthodox learning-teaching approaches toenhance the thinking abilities, social abilities as well as the individual abilities of the sons anddaughters of the county.
Dr. Indira Lilamani GinigeAssistant Director General (Curriculum Development),Faculty of Science and Technology ,National Institute of Education,Sri Lanka.
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Direction: Prof. J W Wickremasinghe - Director General
Guidance: Dr. I. L. GinigeAssistant Director GeneralFaculty of Science and TechnologyNational Institute of Education
Supervision : Mr. C M R AnthonyDirectorDepartment of Science, Health & Physical Education
Instructional leadership, Co-ordination and Editing :Mr. C M R Anthony - DirectorMr. G H Gauthamadasa - Chief Project OfficerMr. W A D Rathnasuriya - Chief Project OfficerMr. W A Sumathipala - Project OfficerMs.J Athamlebbe - Project OfficerMr. A D A de Silva - Project OfficerMr. L K Waduge - Project OfficerMr. P Malavipathirana - Project OfficerMs. Nadee Ama Jayasekera - Project OfficerMs. H M Mapagunaratne - Asst. Project Officer
Translation : Mr. R.B.A.JayasekaraComputer page setting : Mr. K.Wimalasena, Mahinda College, Galle.Art : Ms. U L N Fernando
Teacher Service,Sirimavo Bandaranayake BV. Colombo.07.
Cover page and pictures : Master. Soraj Dhananjaya Kolonne,Grade 11, Thurstan College, Colombo.
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Contents
Page
² Director General’s Message iii
² Preface iv
² Contributors vi
² Contents vii
² School Policies and Progammes 15
· Learning-Teaching Methodology
² Introduction 18-20
² Quality Inputs 21
² Activity Continuum 22-114
· Assessment and Evaluation
² Introduction 117-118
² Tools for Extended Learning 119 -124
² Prototype Questions 125 -129
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Competency 1.0 ((((( Investigates Scientific findings aboutstructure of matter and quantity
Competency level 1.1 ((((( Discuss the scientific findings about the structure ofatom.
Activity 1.1 ((((( Let us go inside the atom.Time ((((( 120 minutesQuality inputs ((((( ² Photograph of a nuclear reactor.annex 1.1.1
² Three copies of instructions for exploration given inannex 1.1.2
• ² Three copies of the article"Let us get insidethe atom"annex 1.1.3
² Demy papers and pastelsTeaching-learning process (((((
Step 1.1.1 ((((( ² Display the photograph to the class.² Inquire from the children as to what know about what is
given in the picture² Conduct a brain storming discussion to highlight the
following.That,² In an atomic reactor,the energy in the atoms is
transformed into energy that is useful to man.² atom is the building blocks of matter.² The findings about the atom can be made use of for the
benefit of man.(15 minutes)
Step 1.1.2 ((((( ² Divide the class into three groups.² Provide the groups with copies of instructions for
exploration.² Assign the tasks and engage the groups in exploration.² Prepare them to present their findings to the class.
(60 minutes)Step 1.1.3 ((((( ² Get each group to present their findings to the class.
² Give the first opportunity to the respective group toelaborate on the presentation.
² Get the other groups to propose constructive suggestions,
² Elaborate highlighting the following points.
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That,² Atom is a particle with a small mass.² Fundamental sub atomic paticles inclued in an atom
are electrons,protons and neutrons.² Out of the paticles the lightest particle is the
electron.² mass of an electron is about 9.1095x 10-31 kg² electron is a particle with a negative charge.² Scientists J.J Thompson,Millikan Cotributed to the
fundamental studies about the electron .² Proton is a partical having a mass of about 1840
times the mass of an electron.² Mass of a proton is about 1.6725x10-31kg² Proton is a particle with a positive charge.² Proton is symbolised as 1
1p² Ernest Rutherford contributed to the fundamental
studies about the proton.² Neutron is a partical which has a mass almost equal
to that of a proton.² Mass of a neutron is about 1.6750x10-20 kg.² Neutron is a particle with no charge,it is neutral.² Neutron is symbolised as 1
0n² The number of electron or the number of protons in
an atom of an element is identical to that element.² According to J.J Thompasons"Plum pudding "model
he stated that an atom is a sphere which is positivelycharged,and the electrons which are negativelycharged are embeded in it.
² According to Rutherford solar model the protons,andneutrons are collected at the centre which is thenucleus and the electrons are moving in orbits aroundit.
² These shells are named as K.L.M.N from centreout wards
(45 mts)
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Criteria for assessment and evaluation² Names and describe the fundamental sub atomic particles.² Appreciates that scientists have contributed to the findings about the atomic structure.² Compare different atomic models.² Collect data about scientific discoveries using references.² Present fact in an alternative way.
Annex 1.1.1
a
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Annex 1.1.2Instructions for group exploration
² Given below are three types of sub atomic particles in an atom.² Electron² Proton² Neutron
² Focus your attention on the sub atomic particle relevant to you.² With reference to the reading material provided to you discuss the follwing about the sub atomic particle relevant toyou.
² It`s discovery² Properties² How it is placed in the atom according to different atomic models.
² Be prepared to present your findings to the class.Annex 1.1.3
Let us go inside the atomAtom is derived from the Greek word "atomos" which means ,not divisible further
but later it was discovered that it is made up sub atomic particles.Although there are many Subatomic particles only three important particles are mentioned below.1& Electron
In the middle of the nineteenth century Scientists drew their attention whetherit is possible to conduct through gases
In 1875 B.C Crooks observed that in a closed glass tube with ends having twoelectrodes and a high voltage is applied and in the meantime the air pressure inside to tube isgradually reduced,there is a glow near the cathode.Further he noticed that if the air pressure isfurther reduced this glow gradually move from the cathode towards the anode,and that there isa"shadow" between the cathode and the anode.When the pressure inside the tube is about 1pascall he noticed that the shadow got distributed throughout the tube and that there is anemission of a beam of rays from the cathode to the anode.Since these rays were emitted fromthe cathode they were named as cathode rays by crooks.This set up is called the cathode raytube.
In (1858BC-1940BC) J.J.Thompson conducted further experiments with theserays,As a result of these experiments following conclusions were arrived at about the prop-erties of cathode rays.
1 Cathode rays move in straight lines.2 They are negatively charged3 They are made up of particles having a mass.
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At present different forms of cathode ray tubes are used in various electronic instruments.Some of these are TV photo tube,Computer monitor,Cathode ray Oscilloscope,Fluorescent tube
Simple Cathode Ray Emitting Tube
Proton
In 1886 B.C. E.Goldstien observed that when using a porous Cathode,is subjected to a voltagefrom 20,000V to 50,000V some special rays were seen to emit from the pores in the Cathode ina direction opposite to the Cathode rays.He named them as positive rays.When ratio e/m was calculated for the particles in these positive rays it was found that the valueis numerically smaller to that of the particles in the cathode rays.
When different gases were used in the Cathode ray tube the e/m ratio for the particles in thepossitive rays were found to be whole numerical multiples of the e/m ratio for the particles in thepossitive rays.When Hydrogen gas is used in the cathode ray tube.In short the lightest possitiverays particles were obtained from Hydrogen.In 1871 B.C-!937B.C Rutherford,named this lightestpossitive ray particle as proton and also that it should be the common possitively charged funda-mental particle of all matter.
Charge of a proton=1.602x10-19C Mass of a proton=1.6726x10-27 KgMass of a proton is 1840 times the mass of an electron.
High Voltage
Cathode
To Vaccum Pump
Anode
J.J.Thompson conducted an experiment to determine the (e/m ) ratio of the cathode rayparticales, where (e) is the charge and (m) is the mass.The value he got for e/m was very large
e/m=1.76x10 c kg-1
The values obtained for e/m ratio for the cathode rays using different gases and different cath-odes is the same.By this Thompson concluded that the cathode rays consists of the sameparticles.Further Thompson stated that,the fundamental unit of electricity,the electron introducedby J.J. Stony in 1874 B.C.is the negatively charge particles in the cathode rays.Electron is a common sub atomic particle present in all atoms. Charge of an electron = 1.602x10-19 C Mass of an electron = 9.1095x10-31 kg
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Neutron
Possitively charged particles named α particles are emitted from radio active sources.When
α
fall on to the instrument to detect charged particals, it causes a deflection.(Fig. a) In 1932 James Chadwick conducted an experiment form which it was founded that when a thin Berylium sheet was place in between the radio active source and the detector no deflectionwas seen ( Fig. b)When a paraffin sheet was place between the Berylium sheet and the detector tere was adeflection. (Fig. c)
High Voltage
AnodeCathode with a slit
production of possitive rays
Source of
α
particals
(a)
(b)
(c)
(d)
Detector
Shows deflectionPossitive chargeparticals fall ondetectorBerylium plateNo deflection isshowncharged particals arenot falling on thedetectorBerylium plate Paraffin wax plate
α
particals Chargeless Neutrons Particals with possitive charge
Shows a deflectioncharged particalsfall on the detector
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Chadwick showed that when α Particles strikes the beryllium sheet it releases particles whichhas no charge.When these particles strikes the paraffin sheet,it releases charged particles andas a result there is a deflection in the detector.(Figd)
He also found that when
α
particles strikes the beryllium sheet,the uncharged particles emittedfrom it has a mass equal to that of the Hydrogen atom. He stated that these particles are anothertype of sub atomic particles and named them as neutrons. mass of a neutron = 1.6750x10-27 kg
s
Thompsons` Atomic Model(Plum pudding model)
Rutherford`s model of the atom(Solar model)
Using
α
rays emitted by radioactive material,in 1911 Geiger and Marsden conducted anexperiment to find the στρucture of matter under the direction of Rutheford.Here a beam of
α
particles was obtained using radio active polonium kept in a lead chamber with a slit.In thisexperiment a thin gold foil was bombarded with particles.They kept a screen painted with Zincsulphide to detect the direction in which the particles move.There was a glow when
α
particles struck the Zinc sulphide sheet.
Rutherford's gold leaf experimentSource of Polonium
Led block with the holeThin gold leaf
Zinc Sulphidescreen whichcould movearound thegold leaf
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Further according to Rutherford possitively charged particles some deviated and some reflectedbecause there are small areas inside atom where possitive charges are collected together.Thesepossitively charged areas he called nucleui.Later Rutherford Put forward a theory accordingwhich he says,electrons are revolving in circular orbits around the nucleus,like the planets arerevolving round the sun.
In this experiment it was discovered that most of the Alpha particals went through the gold foilwithout any deviation, a small number of Alpha particals deviated when going through the goldfoil and a very small number were reflected. The reason why most of the Alpha particals wentthrough without any difficulty was because according to Rutherford a major part of an atom isempty space.
α particals
Reflected
α
particals
Atom
Nucleis
α
particals not diverging
α
particals diverging
Model to explain the results of Rutherfords experiment
electron
nucleus
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Competency 1.0 ((((( Investigates Scientific findings aboutstructure of matter and quantity
Competency level 1.2 ((((( Use Scientific Conventions to highlight diversity inatoms
Activity 1.2 ((((( Let us Investigates about atoms, make models, study aboutdiversity.
Time ((((( 120 minutesQuality inputs ((((( ² Poster showing the planetary modle structure of Helium
and Sodium included in annex 1.2.1² Four copies of instructions for exploration given in
annex 1.1.2² Four copies of the article"Looking at an atom with an
exploratory eye", included in annex 1.2.3² Beads of three colours or small rigifoam balls.,bucket
wires,gum,ekle and thread² Demy papers and pastels
Teaching-learning process (((((
Step 1.21 ((((( ² Display to the class the poster showing the structure ofHelium and Sodium atoms.
² Conduct a brain storming session to highlight thefollowing.facts.That,
² The shells in an atom from nucleus outwards are namedK, L, M, N
² Helium atom has two electrons in the K shellSodium atom has K, L, M, Shells with 2,8,1 electronsrespectively.
• ² The highest number of electrons K,L,M,N shells couldhave is 2, 8, 8,18
² The arrangement of electrons in the shells around the nucleusof an atom is called electronic configuration
² The electronic configuration of an atom is oneconvention which indicate the identify of an atom.
(15 minutes)
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² Provide the class with copies of instructions forexploration.material for making models,the letter,demypaper and pastel
² Assign the tasks and engage the groups in exploration.² Prepare them to present their findings to the class.
(60 minutes)Step 1.2.3 ((((( ² Get each group to present their findings to the class.
² Give the first opportunity to the respective group toelaborate on the presentation.
² Get the other groups to propose constructive suggestions,
² Elaborate highlighting the following points.That,² In Chemistry there are 110 elements discovered at
present.² Every elements is symbolized using the letters in the
English Alphabet.
² Atomic number is the number of protons in thenucleus of the atom.
² In a neutral atom the number of electrons(-charges)and the number of protons (+chargs) areequal.
² In the atomic nucleus both types of sub atomicparticles,protons and neutrons are present.
² In an element the number of protons is constant. Butthere are atoms with varying number of neutrons.
² The total number of Protons and neutrons in thenucleus of the atom is called the mass number or thenumber of nucleons.
² Atoms of an element having identical number ofprotons but different number of neutrons the massnumber varies.These atoms are called isotopes.
² In a chemical symbol of an atom on the top left side isthe mass number and at bottom is the atomicnumber. ( C12
6 )
² The relative mass of an atom is the number of timesthe mass of the atom relative to 1/12 of the mass of
C126
isotope atom.
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² Relative atomic mass=mass of an atom of an element/massof C12
6 isotope atomx 1/12
(45 minuts)
Criteria for assessment and Evaluation² Names and describe conventions related to identification of elements.² Appreciates that diversity of matter is built on diversity of atoms.² Contruct models to show the structure of atoms.² Show diversity by using Symbols.² Discover facts using various Sources.
²
²
K Shell Electronic configuration 2
²²²
²²²
²²² ²²
K Shell
L Shell
M Shell
Electronic configuration 2" 8" 1
Arrangement of sub - Atomic particals in Helium and Sodium He Atom
Na Atom
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Annex 1.2.2
Instructions for group exploration
² Focus your attention to the six atoms assigned to your group, according to the table given below.
Number ofProtons
Symbol A B C D E F G H I J K L M N O P Q R S T U V W X (not the standard )
Data of some atoms
Number of 1 4 1 12 17 19 2 6 7 13 6 18 3 8 11 8 15 20 5 9 10 14 10 16 Electrons
Number of 1 5 2 12 18 20 2 6 7 14 7 22 4 8 12 9 16 20 6 10 10 1412 16 Neutrons
1 4 1 12 17 19 2 6 7 13 6 18 3 8 11 8 15 20 5 9 10 14 10 16
Group i Group ii Group iii Group iv
² Using data given in the table and the artical " Looking at the atom with an exploratory eye" find the standard chemical symbols to the elements provided to you.² Find the atomic mass and mass number of the atoms provided to you by using the types of sub atomic particals and their numbers.² Develope the eletronic configuration of the respective elements by writing the number of eletrons in the cells from closer to the nucleus outwards.² Develope using the letter discuss about isotopes and relative atomic mass and find out the facts.² Select necessary item from the common table and construct solar models of atoms allocated to you.² Be prepared to present constructions and findings to the class.
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Annex 1.2.3
"Looking at an atom with an exploratory eye"
Do you know that all matter solids, liquids and gases found in your environment is formed by110 elements getting grouped together in different ways ?Each of these elements are formed from building units called atoms.Although it is not possible tolook at an Atom or its interior using the naked eye, the way the scientists by performing variusexperiments have been able to learn about the structure of these is amazing. To begin with let usfind about the sub atomic particals of atoms.
Sub Atomic Particals
Element Symbol Number of Number of Num,ber of Electrons Protons Neutrons
Hydrogen H 1 1 --Helium He 2 2 2Lithium Li 3 3 4Berelium Be 4 4 5Boron B 5 5 6Carbon C 6 6 6Nitrogen N 7 7 7Oxygen O 8 8 8Fluorine F 9 9 10Neon Ne 10 10 10Sodium Na 11 11 12Magnesium Mg 12 12 12Aluminium Al 13 13 14Silicon Si 14 14 14Phosparous P 15 15 15Sulphur S 16 16 16Chlorine Cl 17 17 18Argon Ar 18 18 22Potasium K 19 19 20Calcium Ca 20 20 20
Every element has a chemical symbol denoted by letters in the English alphabet. For easy studyit is possible to arrange the number of ptotons in the atomic nucleus of all the elements found inthe world. Now let us find out some theories about atoms.
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Nat
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HHeLiBeBCNOFNeNaMgAlSiPSClArKCa
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6
7
8
8
8
1
2
K L M N1
4
6'9
9
10'8
12
14
16
19
20'2
23
24'3
27
28'1
31
32'1
35'5
40
39'1
40'1
HydrogenHeliumLithiumBeralium
BoronCarbon
OxygenFluvorinNeonSodiumMagnisiumAluminium
SiliconPhosporusSulphurClorineArgonPotasium
Calsium
Data of Elements of atomic numbers 1 - 20
Name ofElement
ChemicalSymbol
AtomocNumber
Number of Electrons in theshells(Electronic configuration)
Massnumber
RelativeAtomicmass
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The atomic number of an element is the number of protons in the atom of that element.(In aneutral atom the number of protons in the nucleus is equal to the number of electrons in theshells.)
Mass number The mass number of an element is the sum of the protons and neutrons in the atomic nucleusof that element,
Relative atomic MassYou could understand that atoms are particles having a very small mass hence it is not usefulin Chemistry to use the international unit of mass,the kilogram in relation to the mass of anatom. Hence the mass of an atom is stated as a relative value of a standard unit.It is called theRelative atomic mass unit.Relative atomic mass Unit = mass of C12
6 Isotope atom 12
The relative atomic mass of an atom is the number of times the mass of that atom in relation tothe relative atomic mass unit.It could be stated as
Relative atomic mass = mass of an atom atomic mass unit
Atomic Number
Relative atomic mass = mass of an atom of an element mass of an atom of C12
6 isotope x 1/12
There are differences between the atoms of the same element.An example of this is the presenceof atoms of elements with same number of protons but with different number of neutrons,Suchelements where the number of protons in the atomic nucleus is the same but the number ofneutrons vary,and as a result they vary in their mass number.These are called isotopes.
A Symbol is used to identify an atom.In an atomic symbol at the top left is the mass numberand at the bottom is the atomic number( C12
6 )
24
Annex 1.2.6Data about some of the isotopes found in nature of some elements
1
1
1
2
2
3
3
5
5
6
6
7
7
8
8
8
10
10
10
16
16
16
1
2
3
3
4
6
7
10
11
12
13
14
15
16
17
18
20
22
22
32
33
34
1
1
1
2
2
3
3
5
5
6
6
7
7
8
8
8
10
10
10
16
16
16
0
1
2
1
2
3
4
5
6
6
7
7
8
8
9
10
10
11
12
16
17
18
HH
H
31
21
11
He
He42
32
Li
Li73
63
B
B115
105
C
C136
126
N
N157
147
O
O
O
188
178
168
Ne
Ne
Ne
2210
2110
2010
SSS
3416
3316
3216
Name ofelement
Atomicnumber
Massnumber
Symbol ofthe isotope
Number ofprotonsin thenucleus
Number ofNeutronsin thenucleus
Number ofElectronsin thenucleus
1
1
1
2
2
3
3
5
5
6
6
7
7
8
8
8
10
10
10
16
16
16
Hydrogen
Helium
Lithium
Boron
Carbon
Nitrogen
Oxygen
Neon
Sulpher
25
17
17
19
19
19
20
20
20
20
20
20
17
17
19
19
19
20
20
20
20
20
20
35
37
39
40
41
40
42
43
44
46
48
17
17
19
19
19
20
20
20
20
20
20
18
20
20
21
22
20
22
23
24
26
28
ClCl
3717
3517
K
K
K
4119
4019
3919
Ca
Ca
Ca
Ca
Ca
Ca
4820
4620
4420
4320
4220
4020
Chlorine
Potasium
Calcium
Competency 1.0 ((((( Investigates Scientific findings about the structureof matter and quantity.
Competency level 1.3 ((((( Explain the Properties of compounds using it`s bonds.Activity 1.3 ((((( Let us Investigates the Properties of compounds using it`s
bonds.Time ((((( 120 minutesQuality inputs ((((( ² Atomic models arranged according to instructions in
annex 1.3.1² Two copies of instructions for exploration given in
annex 1.3.2² Two work stations arranged according to instructions
given in annexe 1.3.3 ² Two copies of the article "Chemical bonds" given in
annex 1.3.4² Demy papers and pastels
Teaching-learning process (((((
Step 1.3.1 ((((( ² Join the atomic models accordingly with the help of thestudents.
² Lead a discussion highlighting the following points.² Bonds are formed between atoms by the electron.² Two electrons join to form a bond between two
atoms.² When a chemical bond is formed ,the atoms that go to
form the bond behave the following fashion.² One atom donates an electron from its last energy
level to the other atom.² The election donated by one atom is accepted by the
other atom.² The positive ion formed by the donation of the eletron
and the negative ion formed by the acceptance ofelectron are attracted.
² When there is no formation of ions,electron pairs areshared between two atoms
² During the formation of bonds the atoms try toachieve the maximum inert gas configuration.
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.² An atom reach the maximum nobel gas configuration by
forming one or more bonds. ² Molecules are formed by atoms joining together by
chemical bonds. ² A molecules consists of two or more atoms which may be
homogeneous or heterogeneous.² When chemical bonds form between heterogeneous atoms
compounds are formed.² It is possible to develop the chemical equation of a com
pound by indicating the different number of atoms in acompound molecule using the symbols of elements.
(15 mts)
Step 1.3.2 : ² Divide the class into two groups.² Provide the groups with instruction for exploration the
article,demy papers and pastel. ² Assign the tasks and engage the groups in exploration.
² Prepare them to present their findings to the whole class.(60 mts)
Step 1.1.3 (((((² Get each group to present their findings to the class.² Give the first opportunity to the respective group to
elaborate on the presentation.² Get the other groups to propose constructive suggestions,² Elaborate highlighting the following points.That,
² Atoms of elements by releasing electrons become positiveions,and by receiving electrons become negative ions.
² The positive ions are named cations and the negative ions asanions.
² There are ions which are formed from a single atom or froma number of atoms.
² Oppositely charged ions are attracted together and therebyforming ionic bonds,
² When ions get together to form a compound,the arrangement of ions in space is called the ionic lattice.
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² The ionic compounds have the following inherent properties. ² Solid crystalline substances made up of ions.
² Have high melting points and boiling points. ² Soluable in polar liquids. ² Conducts electricity in the fused state as well as in solution.
² A molecule is a unit formed by the union of more than oneatom of similar or dissimilar elements.
² Atoms of some elements in the solid state are arranged in adefinite pattern in space.
² The structures which are formed by the arrangement of atomsof elements in a definite pattern are called atomic lattice.
² Some compound molecules,in the solid state,are arranged ina definite pattern in space.
² The structures formed by the arrangement of compoundmolecules in a definite pattern in space are known as molecularlattice.
² When bonds are formed the presence of electrons are indicated by a dottod cross.
² A single bond between two atom is indicated by a short linein between them.
² Depending on the number of electron pair which go to fromthe bond,the bonds are known as single bond,double bond or atriple bond.
² The electron pairs in the valency orbit that do not take part inthe formation of bonds are called lone electron pairs.
² The compounds which are formed by covalent bonds have thefollowing properties.² Mostly occur as neutral molecules made up of a number
of atoms.² Occur in Solid,liquid,and gaseous state.² Most compounds have low melting points and boiling
points.² Some are soluble in water.² Do not conduct electricity in aqueous solution.
² The ability of an element to combine or its combining power iscalled valency.
² The number of electrons of an atom of an element that takepart in the bonds is equal to its valency.
² Ions as well as radicals have a valency. (45 mts.)
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Criteria for Assessment and evaluation :² Explain how ionic and covalent bonds are formed.² Accepts the fact that there is a relationship between the chemi
cal properties of a compound and the nature of bonds.² Investigates the physical properties of ionic and covalent
bonds.² Use symbols as a method of presenting data.² Make use of models to video concept.
Annexe 1.3.1Instructons to prepare models :Make models,as given in the diagrams,using the rigifoam sheets.
H Na Mg
O O Mg
Cl N
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Annexe 1.3.2 Instructions for group exploration• You are intrested with the exploration of one of the two main groups of classifications of
chemical compounds according to the nature of their bonds.• Covalent bonds• Ionic bonds
• Using the article on chemical bonds,discuss about the nature of the bonds with regard tothe compounds allocated to you.
• Present by using models and symbols how the bonds are formed in the type of compoundsallocated to you giving three examples.
• Calculate the relative molecular mass of the compounds making use of the relative atomicmass.
• Find the combining power of ions,groups of ions or atoms in the compounds provided.• Find out whether there are other compounds which could be developed from these ions,ion
groups,or atoms.• Investegate the solubility in water,physcial nature,heating in the air and conduction of
electricity by an aqueous solution of the compounds in your work station.• Be prepared to present your finding to the class.
Annex 1.3.3Instructions for setting up workstations
• Work station 1• Sodium chloride• Calcium hydroxide• Copper sulphate
• Work station 2• Glucose• Ethanol• Urea
• Keep the following materials in both workstations.• water• Two drycells
• One metre of connecting wire • Torch bulb • Two carbon rods • Two beakers • Tin cover and holder • Burning spirit lamp
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Annex 1.3.4
Chemical bonds
Ionic bonds,ionic compounds and their properties.
An ion is a positively or negatively charged atom or a cluster of atoms.Na atom Na+ ion + eMg atom Mg2+ion + 2eCl atom + e Cl- ionS atom + 2e S2-ion
Examples for ions formed by a cluster of atoms are given below.These are known as ionradicals.
Ammonium ion(NH4)+
Nitrate ion(NO3)-
Sulphate ion(SO4)2-
Phosphate ion(PO4)3-
In electric fields positive ions are attracted to the cathode and the negative ions to the anode.Assuch if the charge in the ion is positive it is called a cation and if the charge is negative it is calledan anion. Ionic bonds is formed between positive ion formed by donating completely one ormore electron in the outer most shell of one atom to another atom,and the negative ions formedby accepting those electrons.This is due to electro statatic attraction between the oppositelycharged ions. Consider following examples.
Ionic compounds have the following endemic properties.• consist of ions which are oppositely charged.• Mostly occur as crystalline solid substances.
Sodium Atom Chlorine Atom Sodium ion Chloride ion
(Na) (Cl) (Na+) (Cl-)
²² ²²
²²²²
²²²
²××××× ××××××××××
××××××××××
××××××××××
×××××××××××××××
²²²² ²²²
²²²
²²²
××××× ××××××××××
××××××××××
××××××××××
×××××××××× ×××××
²²²² ²²²
×××××
²×××××
→
²
1. The Nature of Bonding in Sodium chloride
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Lithium ion× ×× ×× ×× ×× ×
× ×× ×× ×× ×× ×
××××××××××
×××××
××××ו •
2-
O
+ +•
•
Li
•
•
Li
2' The Nature of Bonding in Lithium Oxide
× ×× ×× ×× ×× ×
× ×× ×× ×× ×× ×
××××××××××
×××××
×××××
•
•
•
•
•
•
Li LiO
Oxygen AtomLithium Atom Lithium Atom
Lithium ion
Oxide ion
Calcium Chloride ̂ CaCl2&
(Mg)2+→
Magnisium Oxide ̂ MgO&
×××××
×××××
O
×××××
×××××Mg O
3' The Nature of Bonding in Magnisium Oxide
4' The Nature of Bonding in Calcium Chloride
(Ca)2+
××××××××××
Cl
Cl
Ca→
Cl×××××
×××××Cl
_
_
2-
Ionic compounds have the following endermic properties.• Consist of ions which are oppositly charged.• Mostly occur as crystaline solide subtances.• High melting points and boiling points.• Most soluble in water.• Conducts electricity in aqueous solutions and in the fused state.(heated and liquified)
Covalent bonds and properties of covalent compounds
A molecule is an electrically neutral cluster of atoms which is made up of more than one atomwhich are of the same element or different elements by sharing electrons.Here the electrons are shared in such a way that the atoms achieve the electronic configurationof noble gases.Each of these shared pair of electrons is a chemical bond.It is indicated by a single short line.
+•H H H × × × × × H•×××××→→→→→
Two Hydrogen Atoms Hydrogen moleculeOuter most shell has one electron One electron pair keep share
In order to obtain of full outer energylevel and gain the electron configurationof the nobel gas Helium
• • • • ××××× ××××× ××××× ×××××
+• Cl
• •
•• Cl
• •
•• Cl
××××× ×××××
××××× × × × × × × × × × × Cl
××××× ×××××
××××× × × × × ×
•×××××→→→→→
Two Chlorine atoms Outer most shell has sevenelectrons
Chlorine molecule (Cl2) One electron pair keep share in orde to obtain of full outer energy level and gain the electron configuration of the nobel gas Argon
××××××××××
××××××××××
²²
²
²
²²
×××××
×××××
××××××××××
O O O O +² →→→→→
²
×××××××××ײ
²
Two Oxygen atoms Oxygen Molecule (O2)Outer most shell has six electrons.
Two electrons pair keep share.In order to obtain of full outer energy level and gain the electron configuration of nobel gas Neon
Two Nitrogen atoms Nitrogen molecule(N2)
×××××××××××××××
××××××××××
²²
²
²
²²
×××××
××××××××××
×××××
N N N N + ××××ײ →→→→→²²²
Outer most shell has five electronsThree electron pain keep share. In order toobtain of full outer energy level and gain theelectron configuration of nobel gas Neon
×××××
× ×× ×× ×× ×× ×
××××××××××
×××××
→
Oxygen atom Two Hydrogen atoms Water molecule ̂ H2O&
×××× ××××× ×
×××× × ×××× ××××× ×
×××× ×
H
²
²
H
H
H²
²
Similarly stucture of water molecule can be shown as follows.
Pay your attention to the nature of bonds of Carbon dioxide and Amonia molecules givenbelow.
× ×× ×× ×× ×× ×
Two Oxygen atoms
Carbon atom Carbon dioxide molecule (CO2)
××××××××××
×××××
× ×× ×× ×× ×× ×
××××××××××
×××××
×××××
×××××
×××××
×××××
×××××
×××××
××××××××××
××××× ×××××
××××× ×××××
××××××××××
→
²
²²
²²
²²
²
×××××
××××××××××
×××××
H
H
H
H H
H
N××××× ×××××
×××××
× ×× ×× ×× ×× ×
→
Ammonia molecule (NH3) Three Hydrogen atoms
Nitrogen atom
N
²
²
²
²
²²
The number of short lines drawn between the atoms shows the number of electron pairsshared by the atoms.If the number of shared electron pairs is one,it called a single bond,if twoa double bond and if three, a triple bond. When the bonds are indicated by short lines theelectrons in the outermost shell which do not take part in bonds should also be indicated.
H-H Cl Cl O O N N
Covalent compounds have the following endemic properties.•Mostly occur as small neutral molecules made up of few atoms.•Occur in the solid,liquid and gaseous states.•Most compounds have low melting points and boiling points.•Some are soluble in water.•Do not conduct electricity in aqueous solution.
Ionic lattice
The structure which indicates how the ions are arranged in a three dimensional space in achemical compound is called an ionic lattice.In the case of some elements the atoms arearranged in a lattice.The structure of arrangement of atoms which are joined by covalencebond is a three dimentional space is called an atomic lattice.Eg1: Carbon-Graphite
Eg. NaCl ionic lattice
•• ••••
••
••
••
••
••
••
•••• ••
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Molecular lattice
some elements which occur as molecules or molecules of compounds sometimes are arrangedin space as a lattice.The structure which indicates the three dimensional arrangement ofmolecules in space is called amolecular lattice.
Eg. Moleculer lattice of Silicon dioxide ( SiO2)
Every atom of carbon in graphite exit in a two dimensionallattice by combining with three other carbon atom by singlebonds.Graphite blocks are formed by arranging these layersone on top of another.The bonds between these layers areweak and as a result one layer could slide over another easily.Because of this graphite is used as a lubricant.
Eg2: Carbon-diamond
In Diamond every carbon atom forms four covalent bondswith four other carbon atoms and as indicated in the diagramin the form of a three dimensional lattice.Diamond has a highvalue because it is the hardest substance in nature and is alsobecause it is a very rare and attractive mineral. Making useof the fact that it is the hardest substance it is used to makedelicate parts of instruments which should not be wastedand in glass cutting.
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The combining power or the combining ability of an element known its' valency. The followingtable indicates the valency of some elements and ion radials.
The chemical formula of a compound is by using symbols and the number of different atoms inthe molecule of the compound,
H2 In the hydrogen molecule there are two hydrogen atoms.Cl2 In the chlorine molecule there are two chlorine atomsNH3 In the Ammonia molecule, there is one Nitrogen atom and three hydrogen atoms.H2SO4 In Sulphuric acid molecule, two atoms of hydrogen, one atom of sulpher and four
atoms of Oxigen
When a compound if formed by atoms of two elements they must be constructed in such away so as to balance the valencies of atom
1 2 3
Ammoinum NH4+
Hydrogen HCO3-
Carbonate
Valency
Lithium Li+
Sodium Na+
Potassium K+
Silver Ag+
Copper^I& Cu+
Hydrogen H+
Fluoride F-
Chloride Cl-
Bromide Br-
Hydride H-
Hydroxide OH-
Nitrate NO3-
Magnesium Mg2+
Calcium Ca2+
Copper(II) Cu2+
Zinc Zn2+
Iron a(II) Fe2+
Lead Pb2+
Barium Ba2+
Oxide O2-
Sulphide S2-
Carbonate CO32-
Sulphate SO42-
Aluminium Al3+
Iron(III) Fe3+
Nitride N3-
Phosphate PO43-
Metal
NonMetal
IronRadical
Example- 1. Sodium chioride is made of univalent Na+ ion and univalent Cl- ion combining .Formula - NaCl2. Magnesium chloride is made by bivalent Mg2+ ion and two
univalent Cl- ions.-Formula- MgCl23. Magnesium oxide is made up of bivalent Mg2+ ion and bi valent oxygen O2- ion combining formula -MgO4. Sodium hydroxide is formed by univalent Na+ combining with uni valent(OH)- ion.Formula-NaOH5. Sodium carbonate is formed by two ions of univalent Na+ and bivalent (CO3)
2- . Formula Na2CO36. Copper sulphate is formed by bivalent Cu2+ combining with bivalent (SO4)
2- ion, Formula CuSO47. Aluminium sulphate is formed by two atoms of trivalent Al3+ ion combining with three ions of bivalent (SO4
2-)ions. Formula Al2(SO4)3
8. Water molecule is formed by two atoms of univalent hydrogen combining with one atom of bivalent oxygen. Formula H2O9. To develop the above formulae the valency of atoms,ions or ion radicals of simple compounds could be made use of,seewhether it is possible to draw a connection between the formula of the compound and the valency of atom or ion radicals using the above example.
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Competency 1.0((((( Investigates the Scientific findings about the structure of matter and quantity.
Competency level 1.4 Use mole to quantify elements and Compounds.Activity 1.4 ((((( Let us quantify matter.Time ((((( 120 minutesQuality inputs ((((( ² An enlarged copy of data table given in annexe 1.4.1
² Two copies of instructions for exploration given inannexe 1.4.2
² Demy papers and pastels
Teaching-learning process (((((
Step 1.4.1 ((((( ² Asks from the students that if the mass of a two rupee coin is8g what is the easiest way to seperate ten thousand of thosecoins.
² Exhibit the data table to the class.² Direct students to get together in group of two and calcu
late the number of atoms in a relative mass of an atom,ingrammes,or the number of molecule in grammes.
² Lead a discussion highlighting the following facts.² The number of atoms in a relative atomic mass of an
element in grammes has been calculated to be about6.022x1023
² The number of molecules in a relative molecular massof a compound in grammes has to be calculated to beabout 6.022x1023
² The number of atoms in a relative atomic mass of anelement in grammes or the number of the moleculesin a relative molecular mass of a compound in grammesis 6.022x1023
² A mole of a substance is 6.022x1023 fundamental entities of that substance6.022x1023ffundamental units which make up matter,theatom,molecule,ion,subatomic particles is called a moleof that matter.
² Mole is an international unit which measure the quantity of matters.
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² The number of fundamental units included in a mole is constant,this constant called the Avogardo Constant(L or NA)
((((( ² Avogadro constant is NA= 6.022 x 1023 mol-1
² The mass of a mole of substance is called the molecular mass of that substance.(M)
Eg.In a mole of carbon atom mass of 6.022x1023
carbon atom is 12g Hence molecular mass of carbon is 12gmol-1
Eg.In a mole of water there are 6.022x1023 moleculesof water.Its` mass is 18g.Hence the molecular massof water is 18gmol-1
² The value of the mass of an element when stated ingrammes is equal to the relative atomic mass of thatelement.
² The value of the mass of a mole of compound whenstated in grammes is the relative molecular mass of thatcompound.
² When it is required to weight substance of small masslike atoms,molecules ,it is easy to weight the requiredamount of that substance.
² When we want to seperate a quantity of substance,theknowledge of the molecular mass of that substance isuseful.
(15 minutes)Step 1.4.2 ((((( ² Divide the class into three groups.
² Provide each group with copies of the article instructions for exploration,demy paper and marker pens.
² Assign tasks and engage groups in exploration. ² Prepare them to present their findings to the class.
(60 minutes)Step 1.4.3 ² Get groups to present their findings to the class.
² Give the first opportunity to the respective group to elaborate on the
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presentation. ² Get the other groups to propose Constructive suggestions. ² Summerize highlighting the following points.
² If the mass of an element/compound(m),and the number ofmoles of Atoms/molecules(n)The relationship is n=m/M
² The mass of a quantity of moles(n)of an element /compound is(m),we get the following relationship.
m = Mxn² The mass of an (N) number of atoms of an element is(m),
The relationship we get ism = MxN/NA
² The relationship we get when a mass(m) of an element/com pound contain(N) number of molecules is
N = (m/M)xNA
² When (n) number of moles of an element/compound contain(N)number molecules the relationship is
N = nxNA
² The relationship of mass of an atom /molecule(m0) is shown bym 0= M/NA.
² When it is required to get a specific quantity of matter andquantitative calculations in chemistry,the above relationships are useful.
(45 mts)
Criteria for assessment and Evaluation² Define the terms mole,Avogadro constant and molecular mass.² Accepts that in chemistry when there is a need to quantify elements/compounds.² Develop relationsship associated with quantitative of elements and compounds.² Shows relationalships using equation.² Investigates the accuracy of a relationaship.
Annex 1.4.1Data Table
Annex 1.4.2
Instructions for group exploration² Focus your attention to the type of matter given below assigned to your group. ² Element ² Compound² Develop suitable expressions to quantify the matter assigned to you.It is possible to include Avogardo constant NA whereever suitable.
² m0 mass of an electron of element/ mass of a molecule of a compound whose molecular mass is M² mass m of an element/compound contains n moles of atoms/molecules whose molecular mass is M² mass m of an element/compound contains N number of atoms/molecules whose molecular mass is M² In n moles of an element/ compound contained N atoms/ molecules whose molecular mass is M
² By making use of the relationships appropriately, select the problems and final solutions tothe matter assigned to you.² The molecular mass of carbon is 12gmol-1 .Find the number of moles in 10g of carbon.² The releative atomic mass of oxygen is 16.Find the number of atoms in 10g of oxygen.
Element Mass ofa atom/g
RelativeAtomicMass
Compound Mass ofa compoundmolecule/g
RelativeMolecularMass
H
C
N
O
1.66 x 10 -24
1.99 x 10 -23
2.32 x 10 -23
2.66 x 10 -23
1
12
14
16
H2O
CH4
NH3
CO2
2.99 x 10 -23
2.65 x 10 -23
2.82 x 10 -23
7.31 x 10 -23
18
16
17
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² The molecular mass of nitrogen is 14gmol-1.Find the mass of an atom of nitrogen.² The molecular mass of hydrogen is 1g mol-1. Find the number of hydrogen atoms in 0.1
mol of hydrogen.² The molecular mass of carbondioxide is 44gmol-1.Find the number of atoms in 20g of
carbon dioxide.² The relative molecular of Methane is 16gmol-1.Find the number of moles in 0.2g of
methane.² The molecular mass of water is 18g mol-1.Find the number of moles in 20g of water.
² Be prepared to present your findings to the class.
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Competency 2.0 ((((( Investigates Periodic patterns in properties ofelements.
Competency level 2.1 ((((( Investigates properties of elements change accordingto the atomic number.
Activity 2.1 ((((( Let us investigate the changing patterns in properties ofmatter..
Time ((((( 120 minutesQuality inputs ((((( ² Four copies of instructions for exploration given in annex
2.1.1² Four copies of "Physical properties of matter" table given
in annex 2.1.2² Graph papers demy papers and pastel
Teaching learning process (((((
Step 2.1.1 ((((( ² Display the class an enlarged figure of the diagrambelow.
² Get some of the student to complete the pattern givenabove.
² Conduct a discussion highlighting the following points•² There is a pattern in the change in direction of the
arrow.² After a definite number of squares we come across an
arrow which is directed in a similar direction.² Patterns which occur again and agian at definite
intervals are known as periodic pattern. ² Awareness of patterns simplify science education.
(15 mts)IStep 2.1.2 ((((( ² Divide the class into three groups.
² Provide the groups with explorationinstructions,table,graph papers,demy papers and pastel.
² Assign the tasks and engage the groups in exploration.² Prepare them to present their findings to the class.
(60 minutes)
)
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Step 2.1.3 ((((( ² Get each group to present their findings to the class.² Give the first opportunity to the respective group to
elaborate on the presentation.² Get the other groups to propose constructive sugges
tions,² Elaborate highlighting the following points.
That,² C and Si elements are at the top graph on of melting
points² He,Ne,Ar elements are at the bottom of the graph on
melting points.² According to the graph the variation in temperature of
liquifactors shows a periodic pattern.² Element C and Si are at the top of the graph boiling
points.² Elements He,Ne,Ar are at the bottom of the graph
giving boiling points² According to the graph the variation in boiling points
shows a periodic pattern.² Elements B and Al are at the top of the graph
givining density. ² Elements H,N,Na and K are at the bottom of the
graph giving density.² According to the graph indicating variation in density
shows a periodic pattern.² The volume occupied by a molecular mass of an
element when expressed in cubic centimetres it iscalled the atomic volume.
² In the graph giving the atomic volumes ofelements,He,Na, and K elements are placed at thetop.
² In the graph giving the atomic volumes of elements Band Al elements are placed at the bottom.
² According to the graph, variation in atomic volumesof elements shows a periodic pattern.
² Properties of elements is a periodic function of theatomic number.
(45 mts)
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Criteria for assessment and evaluation² Explain the variation in pattern of temperature of liquifaction/boiling point/density/ atomic volume, of elements against the atomic number.² Appreciates that there is a periodic variation shown by the atomic number against properties of elements.² Draw graphs to show variation of properties of elements.² Explatins a graph.² Makes educational activities easy by understanding patterns.
Annex 2.1.1Instructions for group exploration
² Your group is expected to investigate how one of the properties given below vary according to the Atomic number.
² Melting point of elements² Boiling points of elements² Density of elements² Atomic volume of elements
² Using the table given draw a graph with Atomic number against the respective property.² Enlarge the graph developed by you, and draw on a demy paper.² Be prepared to present your findings to the whole class
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Annex 2.1.2
Physical Properties of Elements
H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
-259
-270
180
1283
2030
3600
-210
-218
-220
-249
97.8
651
660
1410
44
113
-103
-189
63
840
-253
-268.9
1330
3000
2550
4800
-196
-183
-188
-245
890
1100
2500
2400
280
445
-35
-186
766
1500
0.071
0.125
0.53
11.84
2.34
2.25
0.81
1.14
1.15
1.20
0.97
1.74
2.70
2.42
2.34
2.07
2.00
1.66
0.87
1.55
14.1
31.8
13.1
4.9
4.3
5.4
17.3
14.0
17.1
16.8
23.7
14.0
10.0
16.6
14.1
15.5
18.7
24.0
45.0
26.0
Elements Atomicnumber
Meltingpoint/ 0C
Boilingpoint/0C
Densityat 20 0Cg cm-3
Atomicvolumecm3 mol-1
(Source : Book of Data for Teachers of Chemistry / 1989, NIE)
49
Competency 2.0 ((((( Investigates Periodic patterns in properties ofelements.
Competency level 2.2((((( Investigates the realtionship between the position inperiodic table and the properties of elements.
Activity 2.2 ((((( Let us return to the periodic table.
Time ((((( 120 minutesQuality inputs ((((( ² Provide a large elaborate periodic table in annexe 2.2.1
² Four copies of Instructions for exploration given inannexe 2.2.2
² Four copies of "Diversity in Physical and chemicalproperties" of elements in annexe 2.2.3
² Graph papers demy papers and pastelTeaching learning process (((((
Step 2.2.1 ((((( ² Exhibit the periodic table to the class.² Direct the students to observe the data indicated by
symbols,numbers and colours.² Conduct a discussion highlighting the following point.
²The elements are grouped in the periodic table for easy study of element. ²The transverse rows of the periodic table are called periods,they numbered as 1,2,3,4 etc.The vertical rows are called groups and they are numbered I,II,III,IV,V,VI,VII,VIII or O ²The elements are grouped in the periodic table as periods and groups ,according to a foundation based on argument.
(15 mts)
Step 2.2.2 ((((( ² Divide the class into three groups.² Provide the groups with instructions for exploration
graph papers,demy papers and pastel.
² Assign the tasks and engage the groups in exploration.² Prepare them to present their findings to the whole class.
(60 minutes)
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Step 2.2.3 ((((( ² Get each group to present their findings to the class.² Give the first opportunity to the respective group to
elaborate on the presentation.² Get the other groups to propose constructive sugges
tions,² Elaborate highlighting the following points.
That,² The number of electrons in the outermost shell of an
atom of the element is equal to the number of thegroup to which the element belongs.
² The number of shells containing electrons is equal tothe number of the period to which the elementbelongs.
² Most elements to the left hand side of the periodictable are found in the solid state.
² The elements at the top on the right hand side of theperiodic table are in the gaseous state.
² The elements in the left hand side of the periodic tableare mostly metals and when you go forward along aperiod non metals are found.
² When you move down along a group containingmetals there are elements which show strong metallicproperties.
² The density of elements from groups I to IV in 2 and3 periods,increase regularly ,but from V to O itdecrease regularly.
² When we move forward along 2 and 3 periods,theatomic volume decrease up to group III,gradually increase thereafter.
² When we move forward along 2 and 3 periods,fromgroup I to IV the melting point and the boiling pointincrease where as groups V,VI,VII and O theelements have very low melting point and boilingpoints.
² When we move forward along a period,theoxides,chlorids and hydrides changes from ionicto covalent types.
(45 mts)
51
Criteria for assessment and evaluation
² Explain varying patterns of properties of elements when moving forwards along periods and down along groups.² Appreciate that the elements are classified in the periodic table for easy study of properties of elements.² Discovers connection between the position of element in the periodic table and the proper ties of the element.² Understands natural patterns.² Use graphs to present data meaningfully when it is suitable.
52
.
Annex 2.2.1
Periodic Table
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Annexe2.2.2Instructions for group exploration
² Your group is assigned to study the relationship between the place in the periodic table and its properties in one of the following.
² moving forward along the second period² moving forward along the third period² moving down along groups I,II,III,IV² moving down along groups V,VI,VII,O
² By using the periodic table and the table privided understand the patterns in the following.² Number of electrons in the outer most shell² Metallic,non metallic,physical state² Density² Atomic volume² Melting point/Boiling point² Acidicity-Basicity of oxides/Hydrides
²Be prepared to present your findings to the class using graphs whenever required.
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Annex 2.2.3
Diversity of Chemical and Physical Properties of elements
Elements AtomicNumber
ElectronicConfig.
Metalic/Non Metalic
Nature ofOxide
Density
gcm-3
AtomicVolume cm-3
mol
meltingpoint 0C
Boilingpoint0C
HHeLiBeBCNOFNeNaMgAlSiPSClArKCa
GaGeAsSeBrKr
1234567891011121314151617181920
313233343536
122, 12, 22, 32, 42, 52, 62, 72, 82, 8, 12, 8, 22, 8, 32, 8, 42, 8, 52, 8, 62, 8, 72, 8, 82, 8, 8, 12, 8, 8, 2
2, 8, 18, 32, 8, 18, 42, 8, 18, 52, 8, 18, 62, 8, 18, 72, 8, 18, 8
0.0710.1250.53
11.842.342.250.811.141.151.200.971.742.702.422.342.072.001.660.871.55
5.905.465.724.803.123.00
14.131.813.1 4.9 4.3 5.417.314.017.116.823.714.010.016.614.115.518.724.045.026.0
11.813.313.116.525.632.3
-259-270 180128320303600-210-218-220-249 97.8 651 6601410
44113
-103-189
63840
30937613220-7.2-157
-253-268.9
1330300025504800-196-183-188-245890
110025002400280445-35
-186766
1500
22372837
68558.5-153
sublimation
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Competency 3.0 ((((( Use chemical reactions appropriatily to fulfilrequirments in life.
Competency level 3.1 Classify chemical recations
Activity 3.1 ((((( Let us understand about types of reactions..
Time ((((( 120 minutesQuality inputs ((((( ² !0 cm3 of concentrated nitric acid
² A copper wire of 30 cm length,half of which is made intoa coil
² Boiling tube² Four work station prepared according to instructions
given in annex 3.1.1² Four copies of instructions for group exploration given in
annexe 3.1.2² Demy paper and pastel
Teaching learning process (((((
Step 3.1.1 . (((((
² Introduce the coiled end of the copper wire into theboiling tube containing concentrated HNO3and display tothe class.
² Direct the students to observe what happens² Conduct a discussion highlighting the following points.
² When conc HNO3 reacts with Cu metal givencoloured Cu(NO3)2 solution is formed and reddishbrown coloured NO2is given out.
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² During chemical reactions ,simple substances areconverted to complex substances or complexsubstances are converted to simple substances.
² The chemical reactions could be grouped accordingto the nature of the reaction.
(15 mts.)
Step 3.1.2 ((((( ² Divide the class into four groups.² Provide the groups with instructions for exploration
graph papers,demy papers and pastel.
² Assign the tasks and engage the groups in exploration.² Prepare them to present their findings to the whole class.
(60 minutes)Step 3.1.3 ((((( ² Get each group to present their findings to the class.
² Give the first opportunity to the respective group toelaborate on the presentation.
² Get the other groups to propose constructive suggestions,
² Elaborate highlighting the following points.That,² Elements Iron and sulphur combine to form sulphide.² Magnesium and oxygen combine to form magnesium
oxide.² When a different compound is formed when an ele
ment-element,or element-compound or compound-compound combine is known as a combinationreaction.
² When potassium permanganate is heated it dissociatesinto simple compounds.
² When hydrogen peroxide is heated it dissociates intosimple compounds.
² When a compound dissociates into simple compoundsor to elements and simple compounds,it is called adissociation reaction.
² Metal magnesium,reacts with copper sulphate releasingCu metal forming Magnesium sulphate.
² Zinc metal reacts with dilute sulphuric acid liberating H2
gas and form zinc sulphate.
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² When an element displace another element in a compoundand takes its place and form another compound it iscalled single replacement reaction.
² When calcium chloride react with sodium carbonatecalcium carbonate and sodium chloride is formed.
² When ferrous sulphate reacts with sodium hydroxide,ferrous hydroxide and sodium sulphate is formed.
² When an element or a radical of a compound,reacts withan element or a radical of another compound undergo anexchange reaction it is known as a doubel replacementreaction.
(60 mts)Criteria for assessment and evaluation² Classify chemical reaction and describe using examples.² Apperciates that chemical changes during a reaction can be made use of to classify chemical change.² Demonstrate chemical reaction.² Data given using symbols are made use of gainfully.² Demonstrate skills in using equipment.
Annexe3.1.1Instructions to set up work stationsSet up four work stations by keeping the following materials.label materials and equipments.Work station 01
² Iron filings 3.5 g² Sulphur powder 1.5g² Boiling tubes 01² Holders 01² Sprit lamp 01² Piece of Magnesium ribbon 01
Work station 02 ² KMnO4 4g ² H2O2 solution 20 cm3
² Boiling tubes 02 ² Holders 01 ² Spirit lamp 01 ² Dry ekle pieces 02
58
Work station 03² 2 cm length of clean magnesium ribbon² Solution of Cuso4(2g of Cuso4 in 100cm3 of water)² Zinc pieces 1g² Dilute H2SO4 acid 10 cm3
² Two test tubes² Test tube rack
Work station 04² CaCl2 solution (CaCl2 0.5g in 10 cm3 of water)² Na2CO3 solution (Na2CO3 0.5g in 10 cm3 of water)² FeSO4 solution(FeSO4 0.5g in 10 cm3 of water)² NaOH solution (NaOH 0.5g in 10 cm3 of water)² Four test tubes² Test tube rack
Instructions for group exploration
² Concentrate your attention on the two reactions assigned to your group.² Heating iron filings with sulphur/burn magnesium in air² Heating of Potassium permanganate/Heating of Hydrogen peroxide² Reaction between magnesium and Copper sulphate/Reaction between zinc and dilute sulphuric acid² Reaction between Calcium Chloride and Sodium Carbonate/Reaction between ferrous sulphate and Sodium hydroxide
² Familiarize yourself with the materials kept at the respective work station.² Conduct the reaction and record your observations.² Write down the equations for the chemical reactions.² Using prefered symbols,develop a common equation to represent both reactions.² Be prepared to present your findings to the class.
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Competency 3.0 :Use chemical reactions appropriatily to fulfilrequirments in life.
Competency level 3.2 : Investigates interaction between matter and electricity
Activity 3.2 : Let us find out connection betwen matter and electricity.Time : 120 minutesQuality inputs : • copper and zink sheet of 2 cm x 5 cm size.
• Fruit (Lime,Orange,Apple) or potatoe yam• LED bulb• Three copies of instructions group exploration given in
annex 3.2.1• Common table prepaired according to instructions in
annex 3.2.2• Demy paper and pastel
Teaching learning process : • Insert the zink and copper sheets into the fruit(Lime,Orenge,Apple) or potato yam, so that they areclose together but not touching. Connect the LED bulbamd demostrate its' glow.
• Conduct a discussion highlighting the following.
• That electricity is produced when subtances in thefruit/potato yam interacts with the metals.
• There is an inter connection between matter andelectricity
(15 mts.)Step 3.2.1 • Divide the class into three groups.
• Provide the groups with instructions for exploration,demy paper and pastels.
• assign the tasks and engage the groups in exploration.• Prepare them to present their findings to the whole class
(60 mts.)
Step 3.2.2 : • Get the group to present their findings to the class.• Give the first opportunity for elaboration to the respec
tive group which made the presentation.• Get the other groups to propose constructive suggestions
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• Elaborate highlighting the following points.
• The following observations were noted when Copper(II) Chloride solution was electrolyse.
• Copper was deposited on the electrode connected tothe negative terminal of the battery.Cu2+ (aq) + 2e Cu(s)
• Chlorine gas was liberated at the electrode connected to thepositive terminal of the battery.2Cl - (aq) + 2e Cl2 (g) + 2e
• When a moist litmus paper was exposed to Chlorine gas itdecolourised.
• The green colour of the solution grsduslly redused.• temperature of the system increased.
( 45 mts))
• With lighting of the bulb, flow of current through the electrolytewas confirmed.
• It is possible to change matter by supplying electricity fromoutside.
• Effecting a chemical change at the electrodes by passing acurrent through an ionic solution (electrolyte) is known aselectrolysis.
• During electroplating of the iron plate the following observations were made.• Copper was deposited as a thin film on the iron plate.
Cu2+ (aq) + 2e Cu(s)• Copper plate gradually dissolved.
Cu(s) Cu2+ (aq) + 2e• Colour of the solution did not change• Level of the solution increased.
• The depositing of a metal on a surface is known as Electroplat-ing.
• By electroplating a surface gets a metallic finish and protection.• When bulb is connected between Copper and Zink plates
immersed in dilute sulphuric acid,• The bulb ignited.• Zink plate gradually dissolved.• Gas bubbles got collected on the Copper plate.
• When bulb is connected between Copper and Zink platesimmersed in dilute sulphuric acid, an electric current is pro-duced
• A set up where an electric current is produced, associated witha chemical change is known as an electric cell.
• Electric currrent could be obtained from dry cells and batteries.
61
• Removal of electrons from an atom, an ion or a radical isOxcidation.
• Intake of electron from an atom, an ion or a radical is Reduction.• Electrode where Oxidation is taking place is known as Anode.• Electrode where reduction is taken place is known as Cathode.
(45 mts)Criteria for assesment and evaluation
• Explain about electric cells, electrolysis and electroplating.• Appreciates that it is possible to enhance daily living using the
relationship between matter and electricity.• Investigates the relationship between matter and electricity.• Prepair a diagram with a set up selecting the materials.• Use demostration effectively for communication.
Instruction for group exploration
• Your group is assigned to study the interaction between matter and electricity using one of the following.
• Chemical cells.• Electrolysis• Electroplating
• Study the diagram in the respective precincts , select the necessary materials to prepare the set up from the commen table.
• Make the setup.• .Observe the following and report on the set up relevant to you
• Changes that take place at the electrodes.• Changes in the solution.• Is there a change in temperature during the reaction?• Did the bulb ignit?
• What are the possible ions in the solution provide to you?• Be prepared to present your findings to the class along with a
demostration.
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Annex 3.2.2
Keeping diagrams in the work stations
4 VWork Station 1
+ _
+ _
4 V
+ _
+ _
ZnCu
Bulb
Carbon Electrodes
CuCl2 Aqeous Solution
Work Station 2Eletrolysis
Bulb
Cu ElectrodeFe Electrode
CuSO4Aqeous Solution
Electroplateing
Work Station 3 Bulb
ElectrodeElectrode
Dil. H2SO4 Solution
Chemical Cell
63
α
αα
.
±±
Annex 3.2.3
Materials and apperatus on common table
• Carbon Electrodes 02• Copper electrodes 02• Zinc electrodes 01• 2 cm x 5 cm Iron plate (surface cleaned )• Dry Cells 06• 1.5 V Bulbs 03• Thermometers 03• 100 cm3 Beaker 03• 0.5 mol dm-3 CuCl2 aqeous solution 100 cm3
• 0.1 mol dm-3 Dil. H2SO4 Solution 100 cm3
• 0.1 mol dm-3 CuSO4 Solution 100 cm3
• Litmus papers• Connecting wires
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Competency 3.0 ((((( Use chemical changes suitably to fulfil necessitiesin life
Competency level 3.3 ((((( Investigates reaction patterns of pure metals.
Activity 3.3 ((((( Let us explore the reactivity of metals.
Time ((((( 120 minutesQuality inputs ((((( ² Piece of Sodium metal,knife and a basin of water
² Four work stations prepared according to instrutionsgiven in annex 3.3.1
² Four copies of instructions for group exploration given inannex 3.3.2
² Demy papers and pastelTeaching learning process (((((
Step 3.3.1 ((((( ² Direct the students to observe how a cut surface afreshly cut piece of sodium change with time.
² Demonstrate to the class the reaction between sodiumand water by putting a piece of sodium into a basin ofwater.
² Conduct a discussion highlighting the following points.² Sodium is a pure metal.² When a freshly cut surface of sodium metal is exposed to air for a short time it looses its shine.² Sodium metal reacted vigorously with cold water.² It is possible for the reactivity metals could differ from metal to metal.
(15 mts)
Step 3.3.2 ((((( ² Divide the class into four groups.² Provide the groups with exploration
instructions,table,demy papers and pastel.² Assign the tasks and engage the groups in exploration.² Prepare them to present their findings to the class.
(60 mts)Step 3.3.3 ((((( ² Get each group to present their findings to the class.
² Give the first opportunity to the respective group toelaborate on the presentation.
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² Get the other groups to propose constructive suggestions,
² Elaborate highlighting the following points.² When Mg,Al,Zn,Fe and Cu metals are kept in the air
for a short time there is no observable change.² When Mg is heated it burns with a glowing flame.² When Al, Zn, Fe and Cu are heated in air they loose
their shine.² When Mg, Al,Zn,Fe, and Cu are heated in air it re
acts with the oxygen in the air and forms the oxide ofhe metal.
Eg: 2Mg(s)+O2(g) → 2MgO(s)² Mg metals reacts very slowly with cold water releas
ing gas bubbles.² Al,Zn,Fe and Cu do not show any observable
reaction with cold water ,in a short time.² Mg reacts some what vigorously with hot water
releasing gas bubbles.² Al and Zn reacts very slowly with hot water releasing
gas bubbles.² Fe and Cu does not show any visible reaction with
hot water,in a short time.² When Mg,Al and Zn reacts with water,hydrogen gas
is released forming the hydroxide of the metal.Eg Mg(s)+2H2O(l) → Mg(OH)2(aq)+H2(g)
² Mg,Al,Zn and Fe reacts with dilute acids releasinggas bubbles.
Eg Mg(s)+2HCl(aq) → MgCl2(aq)+H2(g)² Cu does not react with dilute acids.² Due high reactivity of Na ,it is dangerous to heat the
metal in air or react it with acids/Hot water.² A metal whose reactivity is high could displace a
metal whose reactivity is less from an aqueoussolution of it.
Eg: Fe(s)+Cu2+(aq) → Fe2+(aq)+Cu(s)² It is possible to arrange the metals in their order of
reactivity in a series.Cu<Fe<Zn<Al<Mg<Na
² The metal series arranged acorrding to decreas ing reacrivity, is known as the activity series
² Scientists have develope the activiry series , by including metals explore and in addition the other metals as follows
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² The metal series arranged according to decreasingreactivity,is known as the activity series.
² Scientists have developed the activity series, byincluding metals explored and in addition the othermetals as follows.
² Activity series is useful when studying about metals.
.
K
Ca
Build upactivityseries
Na
Mg
Al
Fe
Cu
Au
Zn
Exploringmetal
Na
Mg
Al
Zn
Fe
Cu
Au
Sn
Pb
Hg
Ag
Pt
Introduced metal
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Criteria for assessment and evaluation
² Explanes how the activity of two metals could be compaired² Accepts that sequential arrangement of metals in the series developed, and the activity series in agrement.² Compair the activity of two matals experimentaly.² Come to conclutions basing observations² Able to observe the effect of a factor by controlling the variables.
Instructions for setting up of work stations² Set up four work stations for activities.² Provide the four work stations with the following materials. ² Boiling tube ² Two test tubes ² Test tube stand ² Test tube holder ² Bunsen burner ² Pieces of sandpaper ² Small Scissor ² Cold water and hot water ² Two test tube containing 10 cm3 of CuSO4 solution² Provide the work stations with one of the following ² Six pieces each of Mg and Al ² Six pieces each of Al and Zn ² Six pieces each of Zn and Fe ² Six pieces each of Fe and Cu (Each of these metals must be of the same size as a 2 cm length of Mg)
Annex 3.3.1
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Instructions for group exploration
² For exploration you are provided with one of the following metal groups. ² Mg-Al ² Al-Zn ² Zn-Fe ² Fe-Cu² Observe the reactivity of the metals seperately with the follwing(cut the metal into small pieces when required) ² Air ² Cold water ² Hot water ²Dilute Hydrochloric acid ²CuSO4 Solution² From your observations compare the reactivity of the two metals.² Develop with a discussion a series in the ascending order of reactivity of the two metals provided,along with sodium and gold.² Be prepared to present your findings to the class.
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Competency 3.0 ((((( Use chemical changes suitably to fulfil necessitiesin life
Competency level 3.4 ((((( Use suitable methods for extraction of metalsActivity 3.4 ((((( Let us find about methods for extraction of metals.
Time ((((( 120 minutesQuality inputs ((((( ² Piece of Lead,Lead monoxide,blow pipe,charcoal block
and bunsen burner.² Two copies of instructions for group exploration given in
annex 3.4.1² Two copies of article on "extraction of metals" in annex
3.4.2² Demy papers and pastel
Teaching learning process (((((
Step 3.4.1 ((((( ² Show the class a piece and lead monoxide² Ask from the student about the possibility of turning
lead oxide to lead.² Put some lead monoxide into a hole in the piece of
charcoal block,and direct the bunsen flame to the hole byblowing through the blow pipe.
² Allow students to observe the change.² Lead a discussion high lighting the follwing points.
² Lead is formed by the dissociation of lead monoxideby heat.
² During extraction of some metals thermal methodsare used.
² Other methods too are used for extraction of metals² When selecting a suitable method for extraction it is
important to consider the form in which it is availablein nature and the chemical activity of the metal
(15 mts).
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Step 3.4.2 ((((( ² Divide the class into two groups.² Provide the groups with the article on instructions for
exploration ,demy papers and pastel
² Assign the tasks and engage the groups in exploration.² Prepare them to present their findings to the class.
(60 mts)Step 3.4.3 ((((( ² Get each group to present their findings to the class.
² Give the first opportunity to the respective group toelaborate on the presentation.
² Get the other groups to propose constructive suggestions,
² Summrize highlighting the following points.
² The following points are agreeable for metals at thetop of the activity series.
² Reaction is very high² Because they react fast with air and water they are
kept either immersed in paraffin oil or imeared with aprotective covering.
² They are available in nature as chloride of the metal.² The metal is extracted mainly electrolysing the fused
metal chloride.² The following points are valid for metals at the middle
of the activity series.² Shows medium range of reactivity.² Mainly available in nature ,as oxide of the metal² Carbonate of the metal or Sulphide of the metal.² Metal is extracted by thermal dissociation of
oxides,Sulphides or Carbonates.² The following points are valid for metals at the bottom
of the activity series.² Reactivity is very low.² Available in nature as pure metals,not as com pounds.² Extraction is by separating the metal from the soil particles by physical means.
(45 mts)
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Criteria for assessment and evâlution
² Explain the basic methods of extraction of metals.² Appreciates that there is a connection between the reactivity of the metal,from in which it is available in nature ,and method of extraction² Correlate the place occupied by a certain metal in the activity series and its properties.² Gather facts by using reacting materials.² Present the facts collected in a way understood by the others.
Annex 3.4.1
Instructions for Group exploration² You are expected to make a study of a metal group belonging to the activity series given below.
² Metals with high reactivity
² Metals with middle rate of reactivity
² Metals with low reactivity
² Using the artical supplied to you,gather data according to the headings given below,about the metal group assigned to you ² Availability in nature ² Method of extraction ² How it is stored² Gather data about the metal gold under the headings given above,and compare with metals assigned to you.² Be prepared to present your findings to the class.
Annex 3.4.1
KNaCaMgAl
ZnFeSnPbCu
HgAgPtAu
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Annex 3.4.2 Metal extraction
Ores in which the metal with present as the metal chloride
Ore Main constituentsin the Ore
The metal extracted
Sodium Chloride
Potassium Chloride
Magnesium Chloride
Calcium Chloride
NaCl
KCl
MgCl2
CaCl2
Sodium
Potassium
Magnisium
Calcium
Ores in which the metal is present metal oxide
Types of Ore Much constituentsin the Ore The metal extractor
HaematiteMagnatiteLimoniteBoxiteCupriteTinstons
Fe2O3Fe3O4Fe2O.2H2OAl2O3.2H2OCu2O3SnO2
IronIronIronAluminiumCopperTin
Ores in which the metalis present as the metal carbonate
Types of OreMain constitutentin the Ore The metal extractor
CallamineLimestoneMalkiteAturaiteMagnasite
ZnCO3CaCO3CuCO3.Cu(OH)22CuCO3.Cu(OH)2MgCO3
ZincCalciumCopperCopperMagnisium
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Ores in which the metal is present as metal sulphide
Types of Ore Main constituentsin the Ore
Metal extractor
Copper PyritesZincblentGalenaZinabar
CuFeS2ZnSPbSHgS
CopperZincLeadMercury
Methods of ExtractionElectrolysis of Fused compound
Metal The compound that is electrolysed to extract the metal andthe chemical reaction that take place
Sodium
Available in nature as Sodium Chloride. In the Downs processSodium Chloride id fused and electrolysed. For it to liquify easily it ismixed with Calcium Chloride.
NaCl Na+ + Cl-
² At the anode Cl2 if formed. ² At the cathode Na metal is formed. (the diagrames mention under Sodium extraction)
→→
→→CaCl2 Ca2+ + 2Cl-
PotassiumAvailable in nature as KCl. The metal is obtained byelectrolysing the fused Chloride.
Calcium
Available as CaCO3 in nature. By adding Hydrochloric acid tothis, CaCl2 is formed. Fused CaCl2 is electrolysed in Graphaitecrucible.
² Metallic Calcium is deposited on the cathode. ² Chlorine is evolved at the Anode.
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→
Metal The compound that is electrolysed to extracts the metaland chemical reactions take place
MagnesiumMagnesium Chloride is present in nature as Carnalite in sold deposites;Fused Carnalite is electrolysed in Iron vessels. Here mostly MgCl2undergo electrolysis.
AluminiumAluminiumis present naturally as Boxite. (Al2O3.2H2O) This is purifiedand fused , then it is desolve in purified and fused Cryolite (3NaF.AlF3)It is electrolysed.
2. Reduction of the Ore with Carbon or Carbon Monoxide
Metal Reactions and the way reduction is performed
Iron
Zinc
Tin
Lead
Th Ore Hematite (Fe2O3) is roasted , and the oxide is obtained withoutany vapourising material, These oxide is heated in a blast furnancereduced by Carbon monoxide.
Fe2O3 + 3CO 2Fe + 3CO2(The diagram is mention under Iron extraction)
→
Zinc blend (ZnS) or Calomine (ZnCO3) is roasted in airconvert to the oxide
2ZnS + 3O2 2ZnO + 2 SO2 this oxide is mixedwith Coke powder and reduced.
ZnO + C Zn + CO
The Tinstone (SnO2) Ore is roasted in air and later toasted withCarbon.
SnO2 + 2C Sn + 2CO
Galena (PbS) first converted to Leadoxide.
2PbS + 3O2 2PbO + 2SO2Later , Lead is obtained as in the reaction given below.PbO + C Pb + COPbO + CO Pb + CO2
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Extraction of Sodium
Sodium is extrcted by Electrolysing fused Sodium chloride. To reduced the melting point ofSodium Chloride to 600 0C, it is mixed with CaCl2. The fused solution is electrolysed by usingthe Down's cell.
Chlorine gas
Fused Sodium metalFused Sodium metal
Fused Sodium Chlo-ride and CalciumChloride mixture.
Cylindrical steelcathode
Steel diaphragm toavoide the reaction ofSodium and Chlorine.Carbon (Graphite)anode
Down's cell
The cathode is made of steel and the anode is of Graphite. During electrolysis the followingreactions take place at the electrodes.
Na+ + e Na
At anode 2Cl- Cl2 + 2e
At cathode
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Iron Extraction
The Ore that is frequently used is hematite which contains Iron (111)Moisture,Sulphur.Arsenic are present in the ore as impurities.To remove these the ore isroasted in air.Hematite is then mixed coke. Coke is a type of coal which produced more heat.For this the Ore is mixed with Limestone. The heat required is supplied by coke. Limestonesremove sand in the Iron. This reaction taken place in a blast furnace.
Iron Ore,Coke andLimestones
gas impurities gas impurities
Hot air in Hot air in
Liquid Iron out
Blast FurnaceThe diagram given above show a blast furnace. The mixture is introduced to the furnace at thetop. The temperature in this furnace is more than 1500 0C. The chemical reaction taking placecould be shown step by step as shown below.
1. The Oxygen in the air that enter the furnace with coke react to form Carbon dioxide. C + O2 CO2 2. This CO2 reacts further with Coke and forms CO gas. CO2 + C 2 CO 3. The CO gas reacts with Iron (III) Oxide and form Iron. Fe2O3 + 3CO 2Fe + 3CO2
4. In addition to CO Carbon too reacts with Iron Oxide to form Iron. Fe2O3 + 3C 2Fe + 3CO
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Extraction of Gold
Metals Gold, Platinum, Silver and Mercury usually do not react with other elements chemicallyto form compounds. These metals are called inactive metals and they are found in nature as theelements.
But it is mixed with gravel, sand and other soil particals. The has to be seperated from theimpurities. Gold could be obtained from Quart Ore, river sand or gravel as small peices. Herethe most simple mathode to extract the Gold is to sieve the river sand and gravel. Seeving is aprocess where gravitational mathodes dependent on dencity. During seeving heavy gold metalgets collected at the bottom of the vessel and the gravel and sand gets washed out by the miningwates. Directing the water spout at the gold containes and gold could be extracted.
Another mathod is quarts is powdred and mixed with water , is passed over amalgamated cop-per electrodes. In this process gold is dissolved at the surface of the plate. Later the Mercury isbistilled.
A piece of rock which contains gold
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Competency 3.0 : Use chemical change suitable to fulfil necessity of life
Competency Level 3.5 : Control the rate of chemical reaction
Activity 3.5 : Let us investigate about the factors affecting the rate ofchemical reaction.
Time : 210 mts.
Quality Inputs : • Spakle, Sandalwood stic and a box of matches• Four copies of the two page artical on instructions for
exploration given in annex 3.5.1• Four work station arranged according to instrution given
in annex 3.5.2• Demy papers and pastels
Teaching Learning Process
Step 3.5.1 • Ignit the Sparkle, Sandalwood stic at the same time anddirect the students to observe.
• Discuss about the students observations.• Lead a discussion highlighting the following points.
• When Sparkle and Sandalwood stic were ignited thechemicals present in them burn.
• The rate of burning of Spakle is greater than the rate ofburning of Sandalwood stic.
• There are different factors which could affect the rateof a reaction.
• The rate of a chemical reaction could be decided by thetime taken to decrease a certain quantity of reactants orthe production of a certain quantity of the product.
(15 mts.)
Step 3.5.2 : • Divide the class into four groups.• Provide the group with instrutions for exploration, demy
pastels.• Assign the tasks and engage the groups in exploration.• Prepare them to present their findings to the class.
(60 mts. )
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Step 3.5.3 : • get each group to present their findings to the class.• Give the first opportunity to the respective groups to
elaborate on the presentation.• get the other groups to propose contructive suggestions.• Summerize highlighting the following points.
• In the experiment it is necessary to keep the factorsconstant other than the factor which we are experiment-ing
• In a reactionwhere a gaseous product is obtained todetermine the rate of reaction the volume of gas liber-ated at a definite time interval or the time taken toliberate equal volums of the gas could be measured.
• In the reaction between Magnesium and Acid euqalweights of cleaned pieces of Magnesium ribbon mustbe used.
• When the effect of temperature is determined, equalsizes of clean iron nails, equal volums of KMnO4,H2SO4 acidmust be used and the time taken for theviolet colour to disappear must be compaired.
• When acids are used , precautionary measures for saftymust be taken.
• When considering the effect of temperature the differ-ence in the temperatures of the solutions must be about150 C .
• When Calcium Carbonate (Marble Chips) are used,powder or crystals of equal weight must be taken.
• For the Hydrogen peroxide dissociation reaction arecent production of Hydrogen Peroxide must be used.
• In the experiment to find the effect of concentration onrate of reaction the set up given below could be used.
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Glass Tube
H2
(ii) (iii) (iv)
HCl
RubberBung
Mg ribbon
(i)
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At 60 0C temperature
(i)
(ii)
KMnO4 $H2SO4 Solution
Cleaned Iron nail
At room temperature
MnO2 or Sand
H2O2
Syringe
O2
CO2CaCO3
HCl
• In the experiment to determine the effect of temperatureon rate of reaction the experiment to be set up as givenbelow
• In the experiment to determine the effect of physicalnature of the reactants the experiment could be set upas given below.
• In the experiment to determine the effect of catalysts theexperiment could be set up as given below
(45 mts.)
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Step 3.5.4 : • Set up earlier groups and direct them to work stations• Assign the tasks and engage the groups in exploration.• Prepare them to present their findings to the whole class.
(45 mts.)
Step 3.5.5 : • Get groups to present their findings to the class.• Give the first opportunity for elaboration to respective
groupwhich made the presentation• Get other groups to propose contructive suggestions.• summerize highlighting the following points.
• When Mg reacts with HCl with different concentrations,the time taken to liberate a constant volume of gas decreased with tthe increase in concentration.
• concentration affects the rate of reaction.• when Fe reacts with Acidic KMnO4of same concentration,
with increase in temperature the time taken for the violetcolour in the solution to disappear was less.
• Temperarure affects the rate of reaction.• The time taken for a definit volume of CO2 to liberate when
powdered CaCo3 is less than when the CaCo3 is in thecryslline form.\
• Physical nature of the reactants affect the rate of reaction.• When MnO2 is used, the dissociation of H2O2 increases.• MnO2 acts as a catalyst during dissociation of H2O2• Catalyst affects the rate of reaction.• A catalyst is a constituent itself undergoing a chemical
change or a decrease in weight.• When gases reacts if there is an increase of presure the
frequency of gas molecules colliding increase and as aresult the rate of reaction increase.
• It is possoble to control the rate of a reaction as requiredby controlling concentration, temperarure, physical nature,catalysts and pressure.
• Controlling the rate of chemical reactions it is possible toincrease the productivity and efficieancy in day to activitiesof chemical production.
(45 mts.)Criteria for assesment and evaluation
• Name and explane the factors affecting the rate of areaction.
• Accepts the fact that by controlling the factors affecting therate of a reaction, the reaction rate could be kept at anoptimum level.
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• Set up experiments and test the factors affecting the rate ofchemical changes.
• Conducts activities according to a plan.• Develope self creations by considering the opinions of
others.Annex 3.5.1
Instructions for group explorations - handout 1
• Your group is assigned to find the effect of the following factors on the rate of a chemical reaction.
• Concentration• Temperature• Physical state• catalyst
• Device an experiment to find the effect of the factor using the instrutions and other materials provides in the work station.• Be prepaired to present your plan to the class
Instructions for group explorations - handout 2
• Focus your attention to any proposed changes to the plan you submitted.• Set up apperatus according to plan and carry out experiment.• Report your observations.• Get ready to present your findings to class.
Annex 3.5.2
Instrutions to set up work stations
Work station I - Concentration• 3 pieces of Mg ribbon ( 3 cm )• Sand papers• 3 Boiling tubes• Glass tubing ( about 10 cm)• Rubber stopper• HCl solution of 2 mol dm -3, 1 mol dm-3, 0.5 mol dm-3 concentrations• Stop watch
Work station II - Temperature• 2 Fe nails• KMnO4 solution ( 0.1 mol dm-3)• H2SO4 acid solution (1 mol dm-3)• Water trough containing hot water.• Two boiling tubes.• Measuring cylinder.• Sand paper• Thermometer• Stop watch
Work station III - Physical nature
• Equal weight of Calcium Carbonate crystals and powder.• Dilute HCl solution• Conical flask• Delivery tube• Rubber stopper• Thistle Funnel• Measuring cylinder• Water trough• Beehive shelf• Stop watch
Work station IV - Catalyst
• Conical flask• Delivery tube• Hydrogen Peroxide solution• Manganese dioxide/ Sand• Syringe ( glass)• Measuring cylinder• Rubber stopper
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Competency 3.0 : Use chemical changes suitable to fulfil necessities of life
Competency level 3.6 : Take steps to prevent metal corrosion
Activity 3.6 : Let us find ways to conserve metal by minimizing corrosion.
Time : 120 mts.
Quality inputs : • Potassium fericyanide and Phenolpthalein• Small quantity of freshly prepared FeSO4 and NaOH• 3 copies of artical on instructions for exploration in annex
3.6.1• 3 work stations arranged according to instructions in annex
3.6.2• Demy paper and pastel
Teaching learning process : • Inquire about their precious knowledge on rusting of iron.
• Add to the freshly prepared FeSO4 solution a few drop ofpotassium ferricyanide and a few drop of phenolpthalien toNaOH solution and show the students.
• Lead a discussion highlighting the following points.• Rusting is due to water and Oxygen reacting with Iron• Acids and salts increase rusting where as bases retard
rusting.• Initial reactions during rusting could be given as follows.
Fs(s) Fe2+(aq) + 2e (Oxidation)
2H2O(l) + O2(g) + 4e 4OH-(aq) (reduction)
• When Potassium fericyanide is added to a solution of Fe2+
solution there is a deep blue colours.• Potassium ferricyanide could be used as an indicator to
detect Fe2+ ions in a medium.• When Phenolphthalein is added to a solution containing
(OH)- there is a pink colour.• Phenolphthalein could be used as an indicator to detect
(OH)- ions in a medium.(15 mts.)
Step 3.6.2 : • Divide the class into four groups.• Provide the groups with instrutiions for exploration, demy
papers and pastels.• Assign the tasks and engage the groups in exploration.• Prepare them to present their findings to the whole class
(60 mts)
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Step 3.6.3 : • Get the group to present their findings to the class.• Give the first oppotunity for elaboration to the respective
group which made the presentation• Get the other groups to propose constructive suggestions.• Summerize highlighting the following points.
• Where the medium turned blue, Iron corrode and formsFe++
• Where the medium turned pink, OH- are formed.
• Where the Iron is in contact with metals above Iron thefollowing occur• Iron does not corrode.• The matal which has the higher reactivity acts as the
anode and undergo corrosion due to Oxidation.• Iron acts as the cathode.• At the iron nail which acts as the cathode there is a pink
colour due to the production of (OH)- iron.• These areas are called ‘cathode areas’• When the metal which has a higher reactivity acts as the
anode and sacrifies itself and prevents iron from rusting,it is called cathode protection.eg. applying zink on iron surface. (galvanizing)
• When any two metals in the activity series are in contactwith one another, the metal which has a higher reactivitycorrode protecting the meatal of lower of reactivitymetal which corrodes is called the sacrificing metal.
• When metals which are below iron in the activity seriesare in contact with iron the following take place.• Iron corrodes vigorously.• Iron acts as the anode and forms Fe2+ by oxidation.
• The blue coloured area near iron nail, which acts as theanode is called the anode area.
• When a metal is coated to prevent it from coming incontact with factors which are necessary for corrosion, andpreventing iron from becoming the anode, it is called anoseprotection.
eg. coating Iron surface with Sn, paint, grease.
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Zn Cu PbMg
Pink Blue
Pink Pink
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• It is possible to keep the ions formed at the cathode andthe anode by using a jelly medium instead of a liquidmedium in the places where they are formed in a experiments where rusting of iron is considered as anelectrochemical change.
• The process of rusting of Iron could be explained by thefollowing reactions.Fe(s) Fe2+
(aq) + 2e2H2O (l) + O2 (g) + 4e 4(OH)-
(aq)Fe(OH)2 (aq) + O2(g) Fe2O3.H2O(s)
• Iron rust is a hydrate Ferric oxide, having a reddish browncolor, a number of water molecules in it vary. As such thecompound is indicated as follows.
Fe2O3.xH2O(s)
(45 mts.)
Criteria for assesment and evalution
• Explain anodic protection and cathodic protection whichprevents rusting of Iron.
• Appreciate that metallic corrosion could be controlled.• Experiments how metals with different reactivity affect corro-
sion of Iron• Arrive at inferences from observation.• Use demostrations as the occasion demands.
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Instruction for group exploration Annex 3.6.3
• Your group is assigned to study about rusting of Iron nailsunder one of the following conditions.• When in contact with Mg and when in contact with Sn• When in contact with Al and when in contact with Pb• When in contact with Zn and when in contact with Cu
• prepair a set up to investigate the rusting of Iron nails when thetwo metals are kept in a jelly medium (Prearation of a jellymedium is given below)
• Device a suitable control experiment.
• Forecast what observations you expect to get after one day.• Take down your observation on the following day.• Arrive at conclutions about rusting of Iron, considering the
place occupied by the metals subjected to the experiment.• discuss why it is necessary to use a jelly medium instead of an
aquaious solution, and the jelly medium should not be allowedto have air bubbles.
• Explain the following phenomena scientifically basing yourconclusion.• when an Iron bucket coated with Zn (Galvanized) gets
scrached rusting is controlled and could be used for a longtime.
• When food container made of Iron sheet and coated withSn get scrached it undergoes rusting very rapidly.
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Petri dish
Jelly medium
Metal piece
Iron nail
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How to prepare the jelly medium
Dissolve a small quantity of NaCl in 250 cm3 of water, add 5g of Agar and while stirring wellboil for about 10 mts. Once the mixture is viscous add 2 cm3 of phenolphthalein, take awaythe beaker from the burner stir and when it is some what cool add 1 cm3 of Potaciumferricyanide and stir further. Before it gets solidified add to petri dishes with Iron nails andallowed to cool. (See that air bubbles do not get into the jelly). It ispossible to use poederedsago instead of jelly.
Annex 3.6.2 Instrution for preparation of work stations.
• Keep the following materials and prepare 4 work stations.
• work station - 1 - Three Iron nails (7 cm) , sand paper, 3 petri dishes, Mg and Snmetal strips 1 piece (size 0.5 cm x 5 cm)
• work station - 2 - Three Iron nails (7 cm), sand paper, 3 petri dishes, Al and Pbmetal strips 1 piece (size 0.5 cm x 5 cm)
• work station - 3 - Three Iron nails (7 cm), sand paper, 3 petri dishes, Zn and Cumetal strips 1 piece (size 0.5 cm x 5 cm)
• Keep at each work station materials required to prepare a jelly medium.
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Competency 3.0 : Use chemical changes suitably to fulfil necessities of life
Comptency level 3.7 : Control burning as appropriate to the occasion
Activity 3.7 : Let us look, find out about burning
Time : 120 mts.
Quality inputs : • Three lengh wise folded half sheet papers, so that they areeasily ignited.
• Three copies of instrutions for exploration article given inannex 3.7.1
• Three work stations arranged according to the instructionsgiven in annex 3.7.2
• Demy paper and pastelTeaching learning Process :
Step 3.7.1 • Ignite one of the lengh wise folded papers and cut just belowthe flame so that the flame is extinguished.
• Moistened the second paper up to two third of it withcoloured water. Ignite the paper at the dry end and display itto the students.
• With the third paper leave the ignited end on a sheet and coverit with an empty jam bottle, allow it to extinguish.
• Lead a discussion highlighting the following points.• The flame extinguished as a result of the burning paper
being cut and removed ( combustible subtance isremoved)• The flame extinguished as a result of the moistend part of
the paper did not reach the temperature required (Ignitiontemperature) for it to burn.
• By covering with the jam bottle the supporter of combus-tion (Oxygen) was prevented from reaching the burningsubtance.
• Three factors essential for conbustion are availability of acombustible subtance, it should reach the ignition tempera-ture and the gas which is the supportes of combustion.
• A chemical reaction where a combutible subtance reactwith a gaseous supporter of combustion liberating heat andlight is called combustiion.
• During combustion, the carbon and hydrogen in the combustible react with Oxygen in the air forming the products ofcombustion.
• Paper is manufactured by plant materials which basicallycontains carbon and hydrogen.
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(15 mts.)
Step 3.7.2 : • Devide the class into three groups• Provide the groups with instrutions for exploration, demy
paper and pastal• Assign the tasks and engage groups in exploration.• Preparee them to present their findings to the whole class.
(60 mts.)
Step 3.7.3 : • Get groups to present their findings to the class.• Give the first oppotunity for elaboration to the respective
group which made the presentation.• Get other groups to propose construtive suggestions.• Summerize highlighting the following points.
• when a candle is burnin, the solid wax melt and it travelsupwards along the wick and gets evaporated. This waxvapour gets dissociate due to heat and these react with thesupporters of combustion in the surrounding air and pro-duce light and heat.
• In the candle flame there are three zones, which could beobserved clearly.
• The inner most zone in the non-luminous zone, it contains amixture of wax vapour and air.
• The temperature in the non-luminous flame is low, whencompared to the other zones.
• The zone outside the non-luminous zone is the luminouszone, here the wax gets dissociated and Carbon monoxideand Hydrogen gas are produced and start to form Carbondioxide and water.
• The tenperature in this zon is higher than the temperature inthe non-luminous zone.
• In the luminous zone, the gases containing Carbon getsdissociated forming free Carbon particals.
• The Carbon particals get into the incandescent state andproduce the endemic yellow colour of the luminous zonegiving out light.
• The zone outside the luminous zone, at the base of the flamea blue colour is clearly visible, but at the top it is invisible. Inthis invisible zone the remaining Carbon monoxide andHydrogen burn.
• In the Kerosene lamp flame,two clearly visible zones, thenon-luminous and the luminous are seen.
• During combustion which carbon react with Oxygen,CO2 is formed and when Oxygen react with hydrogenH2O is formed.
• In the bunsen burner flame, inner most is the non-luminouszone and outer to that the dark blue and light blue zones insequence and outer most is the invisible zone.
• In the bunsen burner at the base the combustible subtanceis made to mix with air and then it is allowed to burn at thetop.
• A combustion reaction in which when there is a supply ofrequired quantity of Oxigen, the combustion substanceCarbon is completly changed to Carbon dioxide. It is calledcomplete combustion.
• A combustion reaction in which when there is a limitedsupply of Oxigen, part of the Carbon in the combustiblesubtance is converted to Carbon monoxide, it is calledparcial combustion.
• In the bunsen burner there is a supply of required quantityof Oxigen, the fuel undergo complte combustion.
• Apart from three types considered earlier, a flame of ahigher could be got from the bunsen burner.
• When combustion takes place in a limited supply of Oxigenthe unburnt Carbon particals are given out from the flame,which could be detected as soot by holding a ceremic brickabove the flame.
• When you hold a wire mesh transversely acroos the flame,due to the absorption of heat by the wire mesh the flame isnot seen above the wire mesh for sometime.
• When yoy hold a glass sheet across the flame in the patchthat forms at the centre unburnt fuel is deposited.
• When you hold a fine metal piece to the outer most zone ofthe flame, there is a reduction in temperature and as a resultthere is partial combustion and turns luminous for a shorttime.
• When you bring a flame to the vapour of an extinguishedflame soon after it was extinguished, the vapour catchesfire.
• In ovens where there are methods to control the supply ofOxigen and fuel, it possible to obtain a flame which showscomplete combustion, with no soot but producing a higherquantity of heat.
• When products of combustion are sent through anhydrousCpper sulphate there is a blue colouration which confirmsthat there is production of water vapour during combustion.
• when the products are sent through lime water, the milkiness shown confirms the production of Carbon dioxideduring combustion.
(45 mts.)
• In the wine spirit flame, luminous flame is not visible.
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Criteria for assesment and evaluation
• Name the zones in the candle flame and explain their nature.• Appreciates that combustion could be controlled depending on
its requirment.• Observe the nature of a flame by simple experiment.• Explane observations scientifically.• Shows interest in the protection of one’s self, the others and
the environment.
Instructions for group exploration
• Your group is entrusted to find the nature of one of the flames.• Flame of oil lamp.• Flame of spirit lamp.• Flame of Kerosene lamp.
• See whether the zones visible in the candle flame and in thebunsen flame are visible in the flame provided to you.
• Engage in the following activities using the flame provided toyou.
• Holding a piece of ceremic brick to the flame horrizontallyabove the flame for about 10 seconds.
• Holding a wire mesh horrizontally across the flame.• Holding a glass slide horrizontally for about 2 sec. across
the flame.• Introduce to the thin colourless outr zone of the flame the
end of a thin wire.• Extinguish the flame and immediately hold the flame of an
ignited splinter close to the wick.• Find the time required for 20 cm3 of water in a boiling tube
to boil.• Compare the nature of the flame provided to you with the
flames of firewood hearth, Kerosene oil cooker and a gasoven.
• In the instances given above the fundermentel componentselements present in the fuel are Carbon and Hydrogen. Thefollowing set up is provided to you to undestand about theproducts of combustion in the flame.
Annex 3.7.2
Instrution setting up work station
• Keep the following materials and set up three work stations.• Piece of ceremic brick• Copper wire guage• Glass slide• Piece of wire 20 cm long.• Box of matches• Candle stick
• In the above work stations, in the first keep coconut oil lamp in the second spirit lamp, in th third Kerosene oil lamp.• Display a burning bunsen burner for all the students in the class to observe.
• Discuss in the group the equipment to be used, procedureto be adopted and observation expected.
• Be prepared to present your findings to the class.
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Competency 3.0 : Use chemical changes suitably to fullfill necessities of life
Competency Level 3.8 : Shows awareness in extinguished firesActivity 3.8 : Prevent fire accidents'Time : 120 mts'Quality inputs : • Incident on ,"Hoe fire became a foe to me" in
annex 3.8.1• Three cop[ies of instructions for group exploration given
in annex 3.8.2• Instruction for arrangement of work stations given in
annex 3.8.3• Artical in annex 3.8.4 on " Let us not fall prey to fire"• Demy and pastals
Teaching- learning process :Step 3.8.1 : • Get a student to precent the incident to class.
• Lead a discussion highlighting the following points.• The possibility of causing fires due to unprotected
bottle lamps.• It is possible for accidental fires to cause deaths or
bodily problems for life times.• When a person who had caught fire to his cloths
run, the supply of Oxygen is better and as a resultcould develop further.
• When clothes catch fire , it is possible to controll thefire by wrapping the body with a gunny bag or athick clothe.
• Fire gets extinguished when one or more factorsshown by the fire trangle are removed.
(15 mts)
Heat
Fuel
Ox
y-
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Step 3.8.2 • Divide the class into three groups.• Provide the groups with exploration instructions , the artical, demy paper and pastel.• Assign the tasks and engage the groups on exploration.• Prepair them to present their findings to the class.
(60 mts)Step 3.8.3 • Get the groups to present their findings to the class.
• Give the first opportunity to the respective group to eleborate on the presentation.• Get other groups to prepare constructive suggestion.• Summarize highlighting the following points.
• Fiires are grouped as follows in order to make it easy to select the the correct fire extinguisher for the respective fire.
• A grade fires - Fires associated with Carbonic compoundslike wood, clothes, paper etc.
• B grade fires - Liquids with highly inflammable like petrolium products, paints, wax, copra, plastic, polithene and grease etc.
• C grade fires - All gasses which are inflammable, like acetylene, L.P. gas, propane, butane etc.
• D grade fires - Fires from metals like Sodium, Potassium Magnesium etc.
• It is possioble to use water fire extinguisher for A grade fires.• Soda - Acid fore extinguisher for A grade fires.• Foam fire extinguisher could be used for B grade fires.• Carbon dioxide fire extinguisher especially suitable for B and C rate fires, and when required for A grade fires.• Halon fire extinguisher could be used for all grades of fires.• Especially for D grade fires and sometimes for C grade fires ( Dry powder ) fire extinguisher could be used.• Water or foam fire extinguisher are not suitable for fires which has a electricity leakage or where there is a possibility of an electricity leakage.• The supply of electricity must be disconnected before any attemp is made to extinguish a fire where there is an electricity leakage or where there is a possibility of an electricity leakage.• In the experimental fire extinguisher water with Carbon dioxide under pressure comes out of the fire extinguisher where Sodium bicarbonate and dilute Sulphuric acid reaction is used.• In the experimental fire extinguisher where Sodium bicarbonte and Aluminium sulphate reaction is used, the foam comes out under pressure.• In the experimental water fire extinguisher a jet of water under pressure comes out.
(45 mts)
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Critaria for assesments and evalution.
• Explane types of fires, instructions for extinguishing fires, instance where there suuitable for use.• Appreciates the fact that the fire extingusher must be chosen depending on the type of fire.• Construct a simple working model of a fire extinguisher.• Shows a tendency to protect from accidents.• Learn from experiances of others.
Annex 3.8.1
How fire became a foe to me
I am Acvhala. From my small days I had the habit of getting up early in the morning andhelping mother. As we did not have electricity in our house we used bottle lamps. On this unfor-tunate day too I got up in the morning lighted the oil lamp. When I was going to the kitchen toignite the hearth the bottle lamp fell erom my hand. The kerosene oil get smeared and the flameextended. Mt clothes caught fire. When I was shoutiung and running about the flae increasedfurther. Fortunately I fell down. Mother came running and wrapped me with a gunny bag. Al-though the flames extinguished I was unconseious. I regained consciousses at the hospital. Myhands, legs and face were burn. When I recovered I was left with a folded skin and some bigscars. Whenever I see them it gave me a great pain. I related this story to you, young sisters andbrothers, to redused my pain and also to tell you about how important it is to protect yourselffrom fires.
Annex 3.8.2
Instruction for group exploration
• Draw your attention to the incident assigned to you from the following.• To extinguish of small fire in the stationery stores of the office using the Soda Acid fire extinguisher.• Extinguishing a spreading fire in a fuel filling stations using a foam fire extinguisher.• To controle a fire in carpentry shop using water fire extinguisher.
• Disscus the principal of the allocated fire extinguisher and also how the fire is extinguished.• Arrange the set up of the fire extinguisher allocated to you by using the instruments and the materials provided in work stations.• Be prepared to present to thre class about the activity of the fire extinguisher you set up and your findings you discover.
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Dilute Sulphuric Acid
Sodium bicarbonete solution
Annex 3.8.3 Instruction for setting work stations
Work station - I
Bottle with a large mouth and a stopper to fit with a single holeSmall bottle without a lidA delivery tube bend in shape L, with a jet at the end of it to fit the hole in the stopperDilute sulphuric acidConsentrade solution of Sodiuim bicarbonateClay pot to burn a fireBox of matchesPieces of paper fit to burnPiece of jute threadThe diagram
Work station - IIBottle with a large mouth and a stopper to fit with a single holeSmall bottle without a lidA delivery tube bend in shape L, with a jet at the end of it to fit the hole in the stopperSolution of Aluminium sulphateSolution of Sodium bicarbonate
Aluminium sulpahte
solution
Sodium bicarbonete solution
Clay pot to burn a fireBox of matchesSmall quantity of kerosene oil to burnPiece of threadThe diagram
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Worl station - III
One inch PVC pipe about 25 cmA lid or endcap to close the end3/4 inch wooden handle slightly longer than 25 cmBottom of an old slipperSharp knifeSome PVC gumOne inch Iron nailSmall hammerA clay pot to burn a fireBox of matchesWood which ignite easilyThe diagram
Annex 3.8.4
" Let us not fall prey to fire"
Fire is very essential to man but also it is distructive. Three conditions are necessary forfire to burn. There are , a combustible subtance, heat energy required for it to burn and Oxygen.When a fire is destructive it must immediatly extinguished. For this one or more factors givenabout must be removed. Fire extinguishers are manufactured for this. All fires cannot be extin-guished from a single fire extinguisher. Because of this in order to select the best fire extinguisherthe fires are grouped.
A - grade fires This includes fires caused by materials with contains carbonic compounds like wood, cloths,paper etc.
B -grade firesThis includes fires caused by materials which are highly imflammable liquids, or liquidspetrolium products, paints, wax, copra, plastic, polythene, grease etc.
C - grade firesThis includes fires caused by all inflammeble gasses like Acetylene, LP gas, Propane, Butaneetc.
D - grade firesThis includes fires caused by metals like Sodium, Potassium, Magnesium etc.
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Water fire extinguisher is used in the case of A - grade fires. A large quatity of water is blownto and it behaves as an artificial rain and falls on the whole burning systems. As a result of thewater absorbing heat from the combustible subtaince the fire is extinguished. For small scale firesmanually controlled water fire extinguishers are used. In these water is kept at very high pressureusing Carbon dioxide or Nitrogen.
Soda - Acid fire extinguisher can be used to extinguish A - grade fires. It is arrange in a waythat the Sodium bicarbonate and dilute Sulphuric acid are kept in seperate cylinders. When thesetwo subtances get mixed water and Corbon dioxide are forced out at high pressure. As a resultof Carbon dioxide the fire is prevented from gettin the gas which supports combustion.
Foam fire extinguisher is especialy designed to extinguished B - grade fires. In the foam fireextinguisher thre is artificially prepared foam. When foam at high pressure falls on oil it floatesand prevent the combustible suntance coming in contact with the supporter of combution Oxy-gen.
Carbon dioxide fire extinguisher is manufactured by storing liquid Carbon dioxide at highpressure. In case of a fire the liquid Carbon dioxide is directed on to the fire. By useing this fireextinguisher A,B and C grde fires could be extinguished. When using this fire extinguisher it mustbe used in such way to prevent accidents to the person who is using the equipment and thepeople who are in the fire from inhale Carbon dioxide gas.
Halon fire extinguisher is good to extinguished all fires. It has Nitrogen gas mixed with Halonand liquified. This gas cool the combustible substaince , and the suppoter of combution is pre-vented from reaching it. A special significance of this fire extinguisher ther is no left over ofanything given out from the extinguisher.
Dry fire extinguisher the chemicals subtance used in this are Potassium bicarbonate, Sodiumbicarbonate, Ammonium phosphate and Ternary Eautetic Chloride powder. In this case whenthe dry powder is directed to the fire the chemical reaction in the flame stops, prevent the com-bustible subtance from reaching the ignation temperature. The superter of combution is pre-vented from coming into contact with the combustible subtance, the flame is extinguished.The fire extinguisher is specially suitable for D grade fires and sometimes for C grade fires.
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Competency 3.0 : Use of chemical changes suitable to fulfil necessities of life
Competency level 3.9 : Produce a gas - Examine its properties.
Time : 120 mts.
Quality inputs : • A baloon filled with H2 gas, according to instructions given inannex 3.9.1. and an empty baloon.
• Three copies of article on instructions for exploration given inannex 3.9.2
• Work stations arranged accordind to instructions given inannex 3.9.3
• Demy papers and pastel
Teaching learning process :
Step 3.9.1 : • Take the baloon filled with H2 gas, to the class. (do notmention that it contains H2 gas)
• Give the other baloon to a student and instruct him to blow intoit so that it is of the same size as the H2 filled baloon and tie it.
• Let the students predict as to what would happen when thetwo baloons are released from hand, direct them to observe.
• Lead a discussion highlighting the following points.• Both baloons contain the same volume of gas.• One baloon contain H2 gas.• The other baloon has expired air.• H2 gas is less dense than normal air, as a result the baloon
went up.• Expired air is more dense than normal air, as a result the
baloon went down.• Different gases have different physical and chemical
properties.(15 mts)
Step 3.9.2 : • Devide the class into three groups.• Provide the groups with instrutions for exploration, demy and
pastal.• Assign the tasks and engage the groups in exploration.• Prepare them to present their findings to the class.
(60 mts.)
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Step 3.9.3 : • Get the groups to present their findings to the class.• Give the first oppotunity to the respective groups to elaborate
on their presentation• Get the other groups to propose contructive suggestions.• Summerize highlighting the following points
• H2 gas has the following properties.• Colourless• No smell• Lighter than air• Slightly soluble in water• Doesnot change the colour of moist litmus paper• Burn with a ‘pop’ sound when a burning splinter is
introduced• No colour change with lime water
• It is possible to indicate the chemical reaction between Znand dilute HCl by the chemical equatiion given below.
Zn(s) + 2HCl(aq) ZnCl2 + H2(g)
• O2 gas has the following properties.• Colourless• No smell• Heavier than air• Slightly soluble in water.• Doesnot change the colour of moist litmus paper.• when a glowing splinter is introduced it burns rapidly.
(suporter of combustion)• No colour change with lime water.
• The production of O2 gas by the dissociation of H2O2 byMnO2 is given by the chmical equation given below.
H2O2(aq) 2H2O(l) + O2(g)
• CO2 gas has the following propeties.• Colourless• No smell• Heavier than air• Slightly soluble in water• Moist blue litmus paper turns pink• Extinguish a glowing spliter• Turns lime water milky ( when more gas is bubbled
through the solution become colourless)• The chemical reaction which produce CO2 by reacting
CaCO3 with dilute HCl is given by the equation givenbelow.
CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)
(60 mts.)
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Criteria for assesment and evaluation
• State the properties of O2, H2 and CO2 gases.• Appreciates that gases have varying properties.• Tests the properties of gases.• Prepare a set up illustrated by a diagram• confirms identity by properties.
Annex 3.9.2
Instrutions for group exploration
• Your group is assigned to produce one of the gases given below and find its’ physical and chemical properties.
• Oxygen gas• Hydrogen gas• Carbon dioxide gas
• Using the materials placed in the respective workstations, instruments and the diagram prepare a set up to produce the gas assigned to you.• Conduct the following tests to understand the properties of the gas.
• Introduce into the gas a glowing splinter with the flame extinguished and a glowing splinter with the flame.• Hold to the gas moistened blue and red litmus papers.• Bubbling the gas throuh lime water.
• State your observation in each of the instances.• Arrive at conclusions about the properties of the gas from your observations.•Be prepared to present your findings to the class.
oooo
Baloon with H2
Bottle
WaterNaOH solution
Pieces of Aluminium
Annex 3.9.1
Getting a baloon filled with H2
Tub
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Annex 3.9.3
Instructions to set up work stations
• Prepare three workstations and provide with materials necessary to set up an experiment as given in the illustration below.
• Provide each workstation with a illustration of the experiment, two test tubes, lime water, Red and Blue litmus papers, splinters and box of matches.
Work station - 01
• MnO2• H2O2• 2H2O2 (aq) 2H2O(l) + O2(g) (In a display board)
Work station - 02
• Zn turnings• Dilute HCl acid• Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g) (in a display board)
Trough
Thistle funnel
Conical flask
Delivery tube
Gas jar
Beehive shelf
Water
Mno2
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Work station - 03
• CaCO3• Dilute HCl acid• CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)
(In a display board)
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Competency 3.0 : Use chemicals reaction appropriately to fulfil requirmentsin life.
Competency level 3.10: Investigates experimentally changes in heat associated withchemical reactions.
Activity 3.10 : Let study the changes in heat associated with chemical changes.
Time : 120 mts.
Quality input : • Two test tubes, two glass rods, 2g each of Glucose andSodium hydroxide
• Four work stations arranged according to the instrutions givenin annex 3.10.1
• four copies of instrutions for exploration given in annex 3.10.2• Demy papers and pastel
Teaching - learning process :
Step 3.10.1 : • Get two students in front of the class and give a test tube withwater and a glass rod to each.
• Provide one student with some Sodium hydroxide and theother some Glucose and allow them to dissolve them in thewater and instruct them to report to the class any observationsabout change in temperature.
• Conduct a discussion highlighting the following.• Temperature of the solution increased when Sodium hy
droxide was dissolved in water.• Temperarure of the solution decreased when Glucose was
dissolved in water.• Change of heat ia associated with chemical changes.• It is possible to calculate the change in heat by using change
in temperature of the solution.• If the change in temperature is q , mass of the solution in m
the specific heat capacity c , the heat change is Q isexpressed by the equation,Q = mcq
• The specific heat capacity of water is 4200 kJ0C-1kg-1
• Mass of 1 cm3 of water is 1 g, (15 mts.)
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Step 3.10.2 : • Devide the class into four groups• Provide the groups with instrutions for exploration, demy
paper and pastel• Assign the tasks and engage groups in exploration.• Prepare the groups for whole class presentation.
(60 mts.)
Step 3.10.3 : • Get the groups to present their findings to the class.• Give the first oppotunity for elaboration to the respective group
which made the presentation.• Get the other groups propose construtive suggestions.• Summerize highlighting the following points.
• If heat is given out during a chemical reaction the tempera-ture of the reacting mixture increase.
• Reaction which liberate heat during reactions are exother-mic reactions.
• If heat is absorbed during a chemical reaction the temperature of the reacting mixture decrease.
• Reactions which absorb heat during areaction are endother-mic reactions.
• In an exothermic reaction, the energy in the product is lessthan that of the reactants.
• In an endothermic reaction the energy in the products ismore than more than that of the reactants.
• It is important to use quatities of reactanta which showpractically measurable temperature difference.
• In this experiment we hypothesize that,• The entire quantity of heat associated with the reaction
was used to change the temperature of the reactingmixure.
• Heat capacity of solutions is equal to the heat capacityof water.
• The density of the solution is equal to the density ofwater.
• Change of heat calculated in a reaction, change with thephysical nature of the product and reactants.
• Therefore when change of heat associated with a reaction isstated it is necessary to indicate the physical state of reac-tants and products.
• To observe a maximum change in temperature the loss ofheat to the enviroment must be minimized.
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• Loss of heat could be minimized by conducting the experiment in an insulated vessel.
• To allow the reactants to mix well, the mixture should bestirred with a stirrer/glass rod.
(45 mts.)Criteria for assesment and evaluation
• Explane with examples, exothermic and endothermic reactions.• Appreciates that there ia an exchange of heat associated with chemical reactions.• Determine experimentally the heat change associated with chemical reactions.• Reach conclusions based on hypothesis.• Investigates the accuracy of conclusions.
Annex 3.10.1 Instructions to prepare work stations
• Have the following set of materials in all the work stations and also specially mentioned items in the respective work stations
• Thermometer• Measuring cylinder• 100 cm3 beaker• Stirrer or glass rod.
Work station - 01
• 50 cm3 of HCl solution (add 8 cm3 of concentrated HCl up to 50 cm3 of water)• NaOH pellets 1g
Work station - 02• 50 cm3 of CuSO4 solution (dissolve 5 g of CuSO4 salt in 50 cm3 of water)• Fe powder 1 g
Work station - 03• 50 cm3 of H2SO4 ( add 3 cm3 of conc. H2SO4 to 47 cm3 of water)• Clean Mg pieces 0.5 g
Work station - 04• NaHCO3 2g• Citric acid about 50 cm3 (dissolve 5g of Citric acid in 50 cm3 of water)
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Instructions for group exploration
• Draw your attention to the following chemical reactions assigned to your group• NaOH(s) + HCl(aq) NaCl(aq) + H2O(l)
• CuSO4(aq) + Zn(s) ZnSO4(aq) + Cu(s)
• H2SO4(aq) + Mg(s) MgSO4(aq) + H2(g)
• NaHCO3(s) + Citric acid (aq) Sodium citrate (aq)+ CO2 (g) +H2O(l)
• Go to your work station and device an experiment to conduct the allocated reaction to determine the heat change.• When handling chemical subtances be careful about the dameges to you and the others.• Calculate the change of heat associated with a molecular mass of the solid state reactant used.
H = 1 Na = 23 Cl = 35.5C = 12 Mg = 24 Zn = 65O = 16 S = 32 Cu = 63.5
• Discuss about the following points.• Errors in the experiment.• How to minimize errors.• Hypothesis used in calculations.
• Be prepared for a presentation of your findings to the class.
Annex 3.10.2
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Competency 3.0 :Use chemical changes in an appropriate way tofulfil living requirments.
Competency level 3.11 :Investigates how weathering of rocks help in the formation of soil
Activity 3.11 :Let us Investigates how weathering of rocks help in theformation of soil
Time : 120 minutesQuality inputs : • Small pieces of granite,quartz,limestone,mica
• Three copies of instructions for exploration given inannex 3.11.1
• Three copies of the article"Earth and rocks" • Demy papers and pastels
Teaching-learning process :Step 3.11.1 : • Small pieces of granite/quartz,limestone and mica are
distributed among the students and directed to observe them.² Inquire from the students how the substances provided
as well as similar substances are subjected to changeConduct a discussion to highlight the following points.That, ² According to observations ,in the piece of granite there
are black coloured and shining components are included in different quantities.
² The piece of granite is a heterogeneous mixture. ² According to observations quartz,limestone and mica
pieces shows homogeneous nature. ² A mineral is a crystalline non carbonic substance which
is homogeneous and having a definite geometric shape and a definite compossition.
² A heterogeneous solid mixture without a definitecompossition and a geometric shape and made up of anumber of minerals is called a rock.
² Due to physical,chemical and biological activities minerals and rockes change into different types.
(15 minutes)
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Step 3.11.2 ((((( ² Divide the class into three groups.² Provide the groups with instruction for exploration the
article,demy papers and pastel.² Assign the tasks and engage the groups in exploration.² Prepare them to present their findings to the whole class.
(60 minutes)
Step 3.11.3 ((((( ² Get each group to present their findings to the class.² Give the first opportunity to the respective group to
elaborate on the presentation.² Get the other groups to propose constructive sugges
tions,² Elaborate highlighting the following points.
That,² It is possible to distinguish three types of rocks, igneous,Sedimentary and metamorphic
rockes.² Igneous rocks are formed from cooling magma
coming from the interior of theEarth.Eg. Basalt.
² Magma coming to the surface of the earth fromempting volcanoes is subjected to rapid cooling,forms igneous rocks,which are made up of smallcrystals.Eg. Granite
² Magma which cools slowly inside the earth formsigneous rocks with big crystals.
² Igneous rocks are very hard and there is indication toshow that they are deposited as layer or grains.
² Weathering of hard rocks result in mineral andcarbonic substances which are deposited as layers atthe bottom of reservoirs.
² When sedemented layers at the bottom are subjectedto pressure from layers above,Sedimentary rocks areformed.Eg. Mudstone,Conglomerate
² The Sedimentary rocks are not as hard as igneousrocks.Eg.Limestone
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• When igneous and sedimentary rocks are subjected totemperature,pressure and movement of the surface ofthe earth,their nature changes and form metamorphicrocks.Eg Marble,slate
• Nature of Metamorphic rocks differs according to theoriginal rock from which it was formed.
• Breaking down of rocks expossed on the surface of theearth into small parts due to physical,chemical andbiological factors is called Weatherning of rocks.
• Rocks are subjected to physical Weatherning due toSun,rain,wind and ice.
• Chemical Weatherning of rocks is when a rock issubjected to a chemical change where compounds init are changed to simple compounds.
• Due to some activities of living beings on rocks,bothphysical and chemical weatherning takes place.
• Soil is formed when sand and clay formed fromWeatherning of rocks combine with Organic matterfrom plants and animals.
• Formation of rocks,and they under go weatherning andform soil ,occur as a cycle in nature.
• Rocks in earth undergo changes from one from toanother in a cyclic movement.
(45 mts)
Criteria for assessment and Evaluation² Explain how soil is formed from weatherning of rocks.²Appreciates that rocks undergo changes in a cycle.² Observe diversity in rocks..²Collect data from sources.² Present data in an attractive way.
Annexe 3.11.1Instructions for group exploration
²Your group is assigned to investigate how one type of rock is formed and how one factor help in the weathering of rocks.
• Types of rocks according • Factors help in to how it is formed weatherning of rocks
• Igneous rocks • Chemical factors• Metamorphic rocks • Physical factors• Sedmentary rocks • Human and other biological
factors
² Discuss in the group about the type of rock you are assigned to you and about the factor that help in the weathering of rock.² Be prepared for a creative presentation of your findings.
Annexe 3.11.2Earth and Rocks
The day for which Anil,Upul and Namal were eagerly waiting for arrived. the three showeda keen interest for Geology. It was for no other reason but the teacher was able to make theclassroom interesting by engaging them in various activities to arouse the interest of thestudents.The trip was organised to educate them about geological resources. Anil started the discussion by stating that"Man`s curiosity about minerals started from thetime he found that implements could be made by stones."But man used pieces of stones tomake stone implements.Rocks found nature are stones which are a combination of one ormo Teacher introduced his friend, geology Professor.He spoke to the three students and said,"Our country is full of resources.out of these resources Geological resources occupy animportant place.Only a minute fraction of it could be found during this trip."As the vehical was moving he showed a granite rock and said,early man may have madeimplements from these.The granite rocks they used to make implements belong to the igneousrocks.In Latin ̀ Ignis`means fire.At a depth of more than 30km from the surface of theearth,the rocks get liquietised or fused due to high temperature.This liquid is knownas`Magma`When this magma comes to the surface of the earth during volcanic eruptions,it iscalled ̀ lava`.When this lava gets cooled and solidified igneous rocks are formed.It is possiblefor this lava to cool inside the earth and form igneous rocks.
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In addition to granite,basalt,rhyolite and obsidian are examples for igneous rocks explained theProfessor.At the moment the vehicle was going along a road .which was constructed recently aftercutting a hill. The Professor instructed the vehicle to be stopped. Professor said"Let us getdown from the vehicle,I will show you something". All of us walked behind the Professor."Can all of you see clearly the layers deposited in this cross section of the hill.Any rock whichis regularly exposed to factors and agents like high heating,high cooling,Sun,Rain,Acid rainbreaking up due to water and wind break up into small particles.This process is calledweatherning of rocks".These settle as logitudinal layers on the surface of the earth,or at thebottom of resoviors or ocean.These layers are called sediments.If these layers are arrangedloosely they occur as gravel,sand on the sea shore and sand dunes,when futher sedimentationon top of these,occur the weight of these layers cause the particles to get tied together andform into rocks.These are called ̀ sedimentary rocks`.Mudstone,Conglomerate and Siltstonesare examples for sedimentary rocks.sometime animal bones and dead bodies of micro organsms with calcareous(calcium carbonate) shells gets deposited for millions of years forms asedimentary rock.,the limestone.These deposits are seen in the Jaffna peninsula and north ofPuttalm,said the teacher,joining the discussion."Does laterite stones (Kabok) belong to thesedimentary rocks"asked Upul. No.we do not consider it as a sedimentary rock because ithas been found that laterite is a product of some type of largely weathered rock which includeclay. When this discussion was going on with the Professor important was taken down in thefield note book.
The group got into the vehocle and restarted the field trip." In Marshy places and inforests with trees, the dead animals and plant materials get collected on the soil. They under gochanges and after millions of years forms coal." questioned Anil
"Son, you raised a very good question."When dead plant and animal matter which is carbonic matter is added to the soil it is decom-posed by microorganisms. sometimes,soft and brown coloured peat is formed from thesecarbonic material after a long period. In our country peat is found in Muthurajawela.Whenpeat inside the earth is subjected to pressure by the layers collecting on top of it,and hightemperature,coal is formed after is long period of time.Since coal is a carbonic material it is notgrouped under as either a mineral or rock.But some scientists include coal as carbonic rocksunder sedimentary rocks.This Process occur in lakes,resoriviors or marshy or Brakish waterhaving environments explained the professor.Then upul asked that in addition to igneous rocks and Sedimentary rocks,their is metamorphicrocks.
The high temperature and pressure inside the core of the earth or movement of the earths`crust or chemical action with other substances and gases rocks undergo changes.
i
As a result of this rocks become metamorphic rocks,explained the teacher.During these change,the mineral composition or the texture(what you see on the surface andwhat you feel when you touch it with your hand) of the rock or both could change.For ex-ample when limestone gets metamorphed it changes to marble said the Professor.Further examples of this are greiss,slate, and quartzite.As namal said at the begining,any typeof rock turns to liquid magma at the core of the earth.where the temperature is about 6600C.That is correct,as magma inside the earth comes to the surface,it is called lava.Igneous rocksare formed from magma or lava.When we look at rocks this way I feel that there is cyclic movement among rock types."I wanted to explain this fact.Any type of rock on the surface of the earth undergo weathringgets deposited as layers and form sedimentary rocks.Similarly rocks into metamorphic rocksdue high temperature,pressure and various chemical changes.The rocks in the core of the earthgets liquified or fused and form magma and in the end form igneous rocks.In this way igneousrocks,Sedimentary rocks,and metamorphic rocks changes from one to the other in a cycle.This is called the rock cycle said the Professor.Heard in another place. This is the containing rocks.In each of these cubicles there is a different type of rock,givethe piece of rock named granite.This is not granite,it is different.This was brought fromScotland.It is dark in colour.Its` crystals are very fine.When lava gets cooled suddenly thishigh quality granite is formed. How about granite in our Country?According to the data discovered by Scientists there is no pure granite in Sri Lanka.But their are ancient stone pillars which are thousands of years old,we see them as if they werebuilt today.Let me see the facts you wrote?The Professor started to read what they had written.Ah.Here is the section written about weathering of rocks.`yes`Very good.Children this is the challange I give you.By refering to different resource materialconstruct an article on"the different ways of weathering of rocks".I give you two weeks fromtoday.There is a Valuable present for the best article and it would be published in theMagazine.
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Identify the charactors of following rocks
SedimentalrocksEg. Sandtone
MetamorphicrocksEg. Schist
IgneousrocksEg. Granite
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T
Rocks break up-Soil is formed
Rocks,which is earths` heritage regularly changes due to various factors and form soil. ThisProcess is known as weathering of rocks.
Physical weatherning of rocks
Due to various factors the rocks on the surface of the earth break up into small parts which isphysical weathering.Heat of the Sun,water,wind are the factors which cause physicalweathering.a) Exporsure of rock to sunlightThe top layers of the rocks exposed to sunlight gets dried up.This is due to Sun`s heat.Duringrain it gets wet.The volume of the rock increase when it is hot and decrease when it iscold.When this process is repeated there is weathering of the rock.
Example.Shalka gal is a sedimentary rock. It is formed by layers arranging one on top of theother.These get regularly dried up and wet,they undergo weathering,as a result the layers ofthe rock break up and ultimately from small partices.
b) Rocks dissolve in waterWhen rocks come in contact with water,some minerals in it gets dissolved.As a result thestructure of the rock gets weak.Because of this the rock breaks up.When carbon dioxide is dissolved in water it is acidic,this cause weathering to take placefaster.
The three friends collected data from various electronic and printed media in addition to factscollected during the trip.not only that,they collected data from books written by SrilankanScientists,and also from compact discs of diffferent encyclopedias and tried to present aresourseful artical. The Artical submitted by Upul got the frist place.It was presented in thefollowing manner.
wõfjkqhsjeiafikqhs ugyß u lrorhs
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c)Heating and cooling of rockesRocks are exposed to Sun during daytime.They undergo expansion due to Sun`s heat.Atnight the rocks get coooled and as a result undergo contraction.Rocks made up of a numberof different minerals undergo weathering in this manner.Different minerals have differentcoefficients of expansion.As a result the bonds between minerals in the rock become less.Thiscauses the surface of the rock to crack.This makes it easy for the rock to break up into smallparts.Water getting into the cracks is also a cause for weathering.d)Sand brought by windsWhen there is a heavy wind,the sand in the sea,and the rivers gets carried by it.When thesesand particles strike the rock small particles of it break off.e)There is physical weathering due to rock particls striking one another in rivers and canals.The pieces of rocks in rivers and canals become rounded due to parts of it getting removed.f)Rain water could enter into the crackes in the rocks caused by various reasons.During thewinter season the water in the crackes turn to ice.The volume of ice is bigger than that ofwater.As a result the crack gets bigger.This causes the rock to split up.Big rocks spilt up intopieces in this way.
Ice
crackgetsbigger
With timethe rocksbreaks up
Temperature fallsbelow 0 0 C
Due to hot and cold climatebig rocks break up into small pieces.
Water getscollectedin the crackes
Whenwaterturn to icethere is
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Chemical weathering of rocksRocks undergo chemical weathering due to the effect of various factors on rocks.The chemicalsubstance cause interaction with the rocks.As a result chemical changes occur in the rocksforming simple compounds.Here oxygen,water,and acidic substances behave a agents ofweathering.These reacton takes place very slowly.
Oxigen in the air cause Iron in therock to corrode
• Formation of new compunds due to the reaction between the rocks and water is called hydration.Hydration too cause weatherning of rocks.• The minerals present in the rocks,sometime undergo hydrolysis.Minerals like Sodium , Potassium,Calcium,Magnesium,Aluminium and Iron undergo hydrolysis. Example:- Hydrolysis of Orthoclas rock yeild Clay.• When Carbondioxide is dissolved in rain water a weak acid is formed.(This is called Cabonization.) This acidic water interacts with minerals in the rock.Here the carbonate of the mineral is formed.This also cause weathering of rocks.
• In a soil where there there is decay of carbonic material by micro organisms the carbondioxide gas is very high.This is because of the activity of microorganisms on the decaying carbonic material.When this carbondioxide,dissolved in water interacts with minerals in the rocks carbonates of the minerals is formed.This cause the weathering of rocks.• You must have seen white,light green,light blue patches growing on rocks.These patches are symbiotic unions between algae and fungi.They are called Lichens.Secretions emitted by these Lichens cause weathering of rocks.• During Lightening, the nitrogen and oxygen react forming nitric oxide and nitrous oxide.These gases dissolve in rain water nitric acid and nitrous acid are formed.Rain water with these acids dissolved is called acid rain.These acids,when they fall on rocks cause weathering.
Eg:- Limestone is weatheredby carbonic acid eventuallycavems are formed
• The oxygen in the air,reacts withminerals which go to form the rock,asa result the rock undergo chemicalweathering. For example as result of the ironpresent in rocks,the rocks undergoweathering.
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Weathering of rocks by living beings
• Living beings,living the same enviroment as the rocks,contribute to the weathering of rocks. When roots of a plant close by grow into a split in a rock caused by physical weatherning the split gets enlarged and the rock is split up.If not,If there is a crevice formed due to chemical weathering which is suitable for plants to grow the roots of the plants increase the split.
• Man cause weathering of rocks by breaking then up.• When micro organisms grow on rocks the chemicals they emit cause weatherning of rocks.• The lichens that grow on partially weathered rocks,physically or chemically,cause the weathering of rock.• Some animals which live associated with rocks dig up the soil around the rock.when rain water gets collected in it cause weathering of the rock. Eg:-Animals dig the soil around the rock.The water that is collected in these places cause weathering of the rocks.• When hooves and horns of animals are periodically rubbed or struck against the rocks,the rocks get worn out.• Reactions caused when excretons matter of animals gets collected on rocks,there is weath ering of rocks.
These tree rots have broken of pieces of
rocks
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Igneous(extrusive)
Igneous(Intrusive)
Magma
Rock ismelted
Sea
IGNEOUS rock is weatheredand carried to the sea by revers
Rock cycle
METAMORPHICrock
Earth movementssquash and burythe layers ofsedimentry rock
SEDIMENTARYrock
According to the states of cartoon nos. (1),(2) and (3) understand the above rock cyclenumber (1),(2),(3).
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Tools for Extended Teaching - Learning Process
1'0 1'0 1'0 1'0 1'0 Evaluation State ( Term 2, Tool 12'0 2'0 2'0 2'0 2'0 Competancy Levels covered ( 1'1" 1'2" 1'3" 1'4
3'0 3'0 3'0 3'0 3'0 Subject content covered ( ² Atom² Sub Atomic particals² Model for Atomic structure² Atomic number² Mass number² Isotops² Electron configuration² Relative Atomic Mass² Chemical bonds² Chemical formula for Molecules² Relative Molecular Mass² Avogardro constance² Mole (as a unit)² Atomic mole² Molecular mole² Molecular mass
4'0 4'0 4'0 4'0 4'0 Nature of Instruments ( Presentation of literature survey5'0 5'0 5'0 5'0 5'0 Objectives ( 1' Skill development as a finder of
new knowledge2' To enhance the skills of reporting observations
as a scientist.3 'To involve in analyzing the reported information
using various criteria.6'0 6'0 6'0 6'0 6'0 Instructions for implementation (
For teacher ( ² This is valid for second term science syllabusin competency level in 1.1, 1.2, 1.3 and 1.4Inform students to litriture survey start of thesecond term.
² In this tool each student is involve in an individualprocess.
² Direct the students subject content or part ofit to each student as your wish.
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² Inform the students in advance the date at whichthey have to submit the completed litreturesurvey.
² Provide constructive suggestions once or twiceby examine their litreture survey before submition
For students ( ² Use litreture review for exploration foractivities nos. 1.1, 1.2, 1.3, 1.4 relevent tosecond term in your science syllabus.
² Select to find information relevent to this topic• Magazine• News papers• CD s• Internet
² Be prepair to present information you havecollected by utilizing available resources.
² Mention the sources which you get theinformation finelly in the litreture reveiw.
² Submitt your litreture review to your teacher ondue date.
7.0 Format for assessment and evaluation:
Criteria
Name of the student
1. Keep information accurately
2. Accuracey of information
3. Report reference sources accurately
4. Follows instructions
5. Prsents the litreture review attractively
Indicate Proficiency Levels as A,B,C or D
A - ExcellentB - GoodC - AverageD - Should Improve
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Tools for Extended Teaching - Learning Process
1.0 Evaluation : Term 2, Instrument 2
2.0 Competency levels covered : 3.7 and 3.8
3.0 Subject content covered : • Action of furance • Fire extingusher and usage
4.0 Nature of Instrument : Preparation of information leaflet
5.0 Objectives : 1. Awearness of using combustion productivity at day to day life. 2. To improve communication skills through informa tion leaflet.
6.0 Instrutions for implementation :
For teachers • Encourage students to make a information leaflet. relevent to " Action of furance and productivity usage"or "fire extinguishers and accurate usage "• Inform student about the source of information.• Get student to refer the inforation leaflet issued by various institutions.
For students • Prepair a information leaflet for public reguarding " Action of furance and productivity usage" or "fire extinguishers and accurate usage"• Mark information which you have been collected in infirmation leaflet concise, simple and atractive.• Submit a prepaired infomation leaflet to your teacher on due date.
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7.0 Format for assessment and evaluation :
Criteria
Names of Students
• Relevance of information
• Presentation skills
• Creativity
• Reliability of information
• Completeness of information
Indicate Proficiency Levels as A,B,C or D
A - ExcellentB - GoodC - AverageD - Should Improve
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Tools for Extended Teaching - Learning Process
1.0 Evaluation : Term 2, Instrument 3
2.0 Competency levels covered : 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.9, 3.10
3.0 Subject content covered : • Classification of chemical reaction • Investigate interactions between matter and electricity.
• Investigate reaction pattern of pure metals• Examine the rate of the reaction of chemical reac tions.• Get the necessary action to prevent metal corrision.• Preparation of gases and examine properties.• Invetigate Heat changes relevent to chemical
reactions
4.0 Nature of Instrument : Chemistry practical workshop
5.0 Objectives : 1. To develope practical experiences relevant to various chemical reactions. 2. To enhance maniuplations skills for setting experi- mental appratus. 3. To direct the students on effective communication through creations.
6.0 Instrutions for implementation :
For teachers • In this tool each student is involved in an individual process as well as group process.• Divide a class into seven groups and give the relevent practical set.• Provide the necessary facilities for practical test and inform the students in advance the date at which they have to conduct a workshop.• Evaluate the students after the workshop.
For students • Present the practical test which is preplaned given by teacher.• Get the chance to present the relevent activity accu rately• Preplanned when the result of experiment is taken several days.• Plan the workshop when result of some experiment is taken several days.
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