STUDY PACK

St. Josephs College

Grade 10

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07. QUANTIFICATION OF ELEMENTS AND COMPOUNDS

Relative atomic mass

The mass of a selected atom taken as the unit and the masses of other elements given

relative to it.

Relative atomic masses of some elements

C - Carbon 12

Na - Sodium 23

Cl - Chlorine 35.5

K - Potassium 39

Atomic mass unit AMU

The mass of the unit to which the masses of other atoms are expressed.

AMU at present

th mass of

isotope

Equation of AMU

AMU =

Relative Atomic mass RAM

How many times an atom weights as much as

th of

isotope

Equation of RAM relative atomic mass unit

RAM =

Calculation of the relative atomic mass of oxygen

The true mass of an oxygen atom 2.66×10-23

g

True mass of a atom is 1.99 × 10

-23g

=

=

= 16.02

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Relative atomic mass of first 20 elements

H 1

He 4

Li 7

Be 9

B 11

C 12

N 14

O 16

F 19

Ne 20

Na 23

Mg 24

Al 27

Si 28

P 31

S 32

Cl 35.5

Ar 40

K 39

Ca 40

Worked examples

Mass of a Potassium atom is 6.476×10-23

, Mass of atom is 1.99×10-23

find the

relative atomic mass of Potassium.

=

=

=

= 39

Mass of an atom of element A is eight times mass of isotope. Find the relative

atomic mass of A.

Relative atomic mass of A =

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Mass of atom A = 8 × mass of atom

Relative atomic mass of A =

= 8 × 12

= 96

Mass of Sodium atom is 3.819×10-23

. The value of the atomic mass unit is 1.66×10-24

find relative atomic mass of sodium

=

= 23

Relative molecular mass (Mr)

How many times a given molecule of an element or a compound weighs as much as

th of C - 12 isotope

Worked examples

Calculation of the relative molecular mass of CO2.

Mass of Carbon dioxide molecule = 7.31 ×10-23

Mass of Carbon atom = 1.99 ×10-23

Relative molecular mass of CO2 =

=

=

=

= 44

Calculation of the relative molecular mass of water.

Mass of water molecule = 7.99 ×10-23

Atomic mass unit = 1.66 ×10-24

=

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=

= 18

Calculation of the Relative Molecular Mass using the formula

Sum of the relative atomic masses is equal to the relative molecular mass of the

molecule.

Element Molecular formula Relative Molecular mass

Hydrogen H2 2 × 1 = 2

Nitrogen N2 2 × 14 = 28

Oxygen O2 2 × 16 = 32

Carbon dioxide CO2 12 + (2×16) = 44

Glucose C6H12O6 (6×12)+ (12×1) +(6×16) = 180

Calculation of the RMM of following compounds

NH3 (14 × 1) + (3 × 1) = 17

H2SO4 (2 × 1) + 32 + (16 × 4) = 98

C12H22O11 (12×12) + (22×1) + (16×11) = 342

Relative formula mass

Ionic compounds that exists as lattices but not molecules have to take the simplest

ratio of constituent atoms

● Mass relevant to their empirical formula

Eg :- NaCl

1 : 1

Calculation of the RMM of following compounds

MgO = 24 + 16 = 40

CaCO3 = 40 + 12 + (16 × 3) = 100

K2SO4 = (39 × 2) + 32 + (16 × 4) = 174

Avogadro constant (L)

The number of atoms in the relative atomic mass of an element

Avogadro Constant = 6.022 × 1023

The mole and the avogadro number

Avogadro Constant (6.022 × 1023

) = 1 mole

Element / Molecule Mass No of moles

Na 23g 1 mole

Mg 24g 1 mole

Glucose 180g 1 mole

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Nitrogen 14g 1 mole

Carbon dioxide 44g 1 mole

Carbon 24g 2 moles

Mole

Amount of substance that contains as many basic building units as there are atoms in

exactly 12g of C - 12 isotope

Molar mass

The mass of a mole of any substance

Unit of molar mass

● Grams per mole (g mol-1

)

● Kilograms per mole (kg mol-1

)

Mass of a mole of any substances

● Relative atomic mass of Sodium (Na) = 23

Molar mass of Sodium = 23g mol-1

● Relative molecular mass of Carbon dioxide (CO2) = 44

Molar mass of Carbon dioxide = 44g mol-1

● Relative formula mass of Sodium chloride (NaCl) = 58.5

Molar mass of Sodium chloride = 58.5g mol-1

● Relative formula mass of Calcium carbonate (CaCO3) = 100

Molar mass of Calcium carbonate = 100g mol-1

Relationship can also used to find the amount of any given substance

Amount of substance Mass of the substance

(number of moles) Molar mass of the substance

n =

Element / Molecule RAM / RMM Molecule (g) Molecule (Kg)

Na 23 23gmol-1

0.023kg mol-1

CO2 44 44gmol-1

0.044kg mol-1

NaCl 58.5 58.5gmol-1

0.0585kg mol-1

Calcium Carbonate 100 100gmol-1

0.100kg mol-1

=

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The number of atoms in 4 moles of Carbon

Number of atoms in 1 mol of Carbon = 6.022 × 1023

Number of atoms in 4 mol of Carbon = 4 × 6.022 × 1023

= 24.09 × 1023

= 2.409 × 1024

The number of atoms in 6 moles of Magnesium

Number of atoms in 1 mole of Magnesium = 6.022 × 1023

Number of atoms in 6 moles of Magnesium = 6 × 6.022 × 1023

= 36.132 × 1023

= 3.6132 × 1024

a) The number of Carbon dioxide molecules in 7 moles of Carbon dioxide

Number of molecules in 1 mole of Carbon dioxide = 6.022 × 1023

Number of molecules in 7 moles Carbon dioxide = 6.022 × 1023

× 7

= 42.154 × 1023

= 4.2154 × 1024

b) The total number of atoms in 7 moles of Carbon dioxide

Total number of atoms = 3

Number of molecules in 1 mole of Carbon dioxide = 6.022 × 1023

Number of molecules in 7 moles of Carbon dioxide = 7 × 6.022 × 1023

Number of atoms in 7 moles of Carbon dioxide = 7 × 3 × 6.022 × 10-23

= 126.462 × 1023

= 1.26462 × 1024

c) The number of oxygen atoms in 7 moles of CO2

Total number of atoms in one CO2 molecule = 2

Number of molecules in 1 mole of CO2 = 6.022 × 1023

Number of molecules in 7 moles of CO2 = 7 × 6.022 × 1023

Number of oxygen atoms in 7 moles of CO2 = 7 × 2 × 6.022 × 1023

= 84.308 × 1023

= 8.4308 × 1024

Motar mass of Carbon in 12g mo-1

find the amount of Carbon in 10g of Carbon

Amount of Carbon in 12g = 1 mol

Amount of Carbon in 1g =

mol

Amount of Carbon in 10g =

× 10

=

= 0.83 mol

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The number of molecules in 0.1 mole of Carbon dioxide.

Number of molecules in 1 mole = 6.022 × 1023

Number of molecules 0.1 moles = 6 × 6.022 × 1023

× 0.1

= 0.6022 × 1022

= 6.022 × 10

21

Reactive molecular mass of Oxygen (O2) is 32. Find the number of O2 molecules in

10g oxygen.

Number of Oxygen molecules in 32g = 1 mole = 6.022 × 1023

Number of Oxygen molecules in 10g =

= 1.88 × 1023

Molecular mass of water is 18gmol-1

. Find the amount of water molecules in 20g of

water.

Amount of water in 18g = 1 mol

Amount of water in 20g =

= 1.11 × 1023

mol

Calculation of the amount of Carbon dioxide in 22g of Carbon dioxide.

(Molar mass of CO2 is 44gmol-1

)

Amount of CO2 in 44g = 1 mol

Amount of CO2 in 22g =

× 22

=

= 0.5 mol

Calculation of the amount of Carbon in 24g of Carbon

Molar mass = 12gmol-1

Number of moles in 12g = 1 mol

Amount of Carbon in 24g =

× 24

= 2 mol

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08. CHARACTERISTICS OF ORGANISMS

Instance Living / Non-living Reason

Hens egg Living If egg is incubated a chick with

living features will be born

A tissue obtained from a

living organism

Livings Budded into another organism

using appropriate methods.

It will show living characteristics.

A fossil of 1000 years

old

Living Can be budded to obtain new

organisms with old characteristics.

Common characteristics of living organisms

Cellular Respiration

Nutrition

Irritability and coordination

Excretion

Movement

Reproduction

Growth and development

Unicellular organisms

Organisms with one cell

Activity to observe cells in pond water and hay extractions

Things needed - pond water sample, hay extraction, light microscope

Method - Each sample was placed on a glass slide and covered with cover

slip and observed through light microscope.

Observation -

In pond water Hay Extraction

Bacteria Euglena Amoeba Paramecium

Organization of unicellular organisms

Organelle level organization can be seen

Structure made of cytoplasm and organelle enclosed by a plasma membrane.

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Development of the embryo of a human using a sketch diagram

Arrangement of different cells in the plant body

Adaptation of a leaf for its functions

CO2 - Presence of stomata, presence of intercellular air spaces

Water - Good water transportation system, well spread roots

Sunlight - Well spread leaves, of chlorophyll, larger surface area

Oxygen - Presence of stomata, presence of intercellular air spaces

Different types of cells

Type of Cell Function Adaptation Diagram

Nerve cell Co-ordination long nerve fibres

Bone cell for keeping the body

erect

long cells

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White blood

cell

Destroying harmful

germs

Ability to produce

antibodies

Red blood

cells

Transportation of

oxygen

Absence of nucleus

by concave shape to

increase surface area

Muscle cells

Movement of limbs Long cell that can

contract and relax.

Gametes

cells

Production of new

organisms

Having in number of

chromosomes.

Ability of moving.

Skin cells Protecting body

from unfavorable

environmental

conditions

Dead cells in outer

surface.

No blood supply.

Define the following

Cell - The structural and functional unit of any living organism

Tissue - A collection of cells

Organ - A collection of tissues

System - A collection of organs

Organism - A collection of systems

Organizational levels of organism considering the blood circulatory system

Organizational Level Example S

Cell

Tissue

Organ

System

Organism

Heart muscle cell

Heart muscle issue

Blood tissue

Heart

Blood circulatory system

Human

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Uses of nutrition

For the production of energy

For obtaining nutrients for the maintenance of life

Organisms obtain energy

By nutrients

Autotrophic organisms

The organisms that have an ability to produce their own food or nutrients

2 types of Autotrophic organisms

Photoautotrophic - Most plants - Mango, Chills

Production of food using solar energy

Chemoautotrophic - Most bacteria

Obtaining energy released from chemical reactions

Photosynthesis

Production of food inside the chloroplast of a plant cell using sunlight

Word equation and the balanced equation of the photosynthesis

Carbon dioxide + Water Glucose + Oxygen

6CO2 + 6H2O C6H12 O6 + 6O2

Different places of storing foods in plants

Stems

Roots

Fruits

Heterotrophic Organisms

Utilized food produced by plants or organic compounds with other living organisms.

Food chain

Linear sequence that starts from a green plant and shows the flow of energy from one

living organisms to the other

Sunlight

Chlorophyll

Sunlight

Chlorophyll

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Example

Grass Grasshopper Frog Snake Eagle

Food web

A collection of food chains

Food web

Respiration

The process by which the stored food is transformed to energy inside the cells

Word equation and the balance equation of respiration

Oxygen + glucose Carbon dioxide + water + energy

C6H12O6 + 6O2 6CO2 + 6H2O + energy

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Demonstrate the removal of Carbon dioxide in respiration

Things needed - Lime water, KOH, Water, 5 equal bottles with corks, glass tubes,

frog (Germinating seeds can be used)

Method - ● The materials were arrange in the above manner

● Water is removed by opening tap from bottle E

Observation - Air enters colour of lime water B does not turn milk, because the

CO2 in bottle A is absorbed by the KOH.

Lime water in bottle D turns milky because of the CO2 released

by the frog.

Conclusion - CO2 is released from respiration

CO2 is byproduct of respiration

Demonstrate the absorption of oxygen in respiration

Things needed - Conical flasks, Glass tubes, Rubber tuber, small test tubes,

beakers, coloured water, Germinating seeds

Method - Following two apparatus were prepared

Observation were taken

Observation - Carbon dioxide released from seeds absorbed by KOH

Oxygen absorbed for respiration

Oxygen is sucked in, through the glass tube

Water level in the tube rises

Conclusion - Oxygen is absorbed in respiration

Absorption volume of O2 is equal to the excretion volume of CO2

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Explain the following

Stimulus - A change which is strong enough to bring about a response

Response - The reaction according to the change in the environment

Sensory organs

The organs detecting the stimuli

Eg :- Eye, Ear, Nose, Tongue, Skin

Irritability

The ability to response to stimuli received from an internal or external environment

Co-ordination

The communication between different organs during the response of stimuli

Important things for co-ordination

Nerves, muscles and hormones

Examples for the response stimuli

Stimuli - A very loud sound (loud music)

Respond - Covering the ears.

Excretion

The removal of the by products from the body that are produced during metabolism.

organ / system excretory product

Skin Sweat (water, salt)

Lungs (Respiratory System) Exhale gas (CO2 + H2O)

Kidney (Excretory System) Urine (water, salt, uric acid, urea)

Main organ responsible for nitrogenous excretion

The kidneys

2 gasses excreted by the plants

Co2 - respiration

O2 - photosynthesis

Explain the following

Anabolism - The process of synthesis of complex compounds from simple

compounds with the living body

Energy is stored during the process

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Catabolism - The process of breaking down complex compounds into simple

compounds in the body releasing energy

Metabolism - The total of anabolism and catabolism

Importance of movements

To fulfill the requirements (food, protection)

locomotive organ of

unicellular organisms

Locomotive organ of multi

cellular organisms

Cilia (paramecium) Fins

Flagella (Euglena) Legs

Pseudopodia (Amoeba) wings

Organism's movement

Movement is a living characteristic of organisms and it is essential for their existence

Mode of Locomotion Responsible Organs

Flying Wings

Walking Limbs (leg muscles)

Running Limbs (leg muscles)

Reproduction

Reproduction is the production of new generation by unicellular or multi cellular

organisms

2 types of reproduction

● Sexual reproduction

● Asexual reproduction

Sexual Reproduction

Gametes of 2 individuals of the same species unit to form a zygote

Asexual Reproduction

A single organism can produce an identical new offspring

Important process for growth of an organism

The increase in number of cell by the cell division

Growth

The irreversible increase of dry mass of the cell

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Development

The increase of complexity of the cell

3 steps in growth and development

● Irreversible increase in size of the cell

● Increase in number of cells by cell division

● Cell differentiation

Activity to observe the growth or a plant

Things needed - A potted plant,

An auxanometer

Method - The materials were places in the above manner. A thread was

connected to a shoot apex of the potted plant and sent through a

pulley and a weight tied onto it.

Observation - After a few days the auxanometer was checked. The indicator has

increase a small amount moved up. (A plant grows slowly, but the

auxanometer shows it at a greater scale)

Conclusion - Plant increase its size with time

For non living things which show living features

Virus

Diagram of a virus

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About the virus

● Very small can be seen only through electron microscope

● 1/1000th the size of a bacteria

● Shows living and non living features

Virus considered as a living and non - living organism

● Shows only one living feature

● Can only reproduce only in living cells

● In environment it exists as a chemical compound

Reproduction of virus using a flow chart

Reaches appropriate living cell host

Releases nucleic acid into cell

Nucleic acid multiplies

Grows protein capsid

Metabolic activity in virus

Does not possess any organelles for metabolic reactions

Viral diseases

Plants Animals

Banana bunchy top AIDS

Curly leaves of chilies Bird flu

Shyamalie Tissera B.Sc (sp) Dip in Education