1. Compositions – water, carbon dioxide

2. Structures

3. Properties – m.p., b.p.

Chemistry is the study of substances

4. Changes – burning, change of state

Stone age Bronze age Iron age

Alchemists : cheap metals gold

Chemistry started as metal extraction

Chemistry in our daily lives1. Clothing – polyester, nylon …..

2. Food – flavourings, colourings and preservatives 3. Housing and daily life – metals, alloys (bronze ..)4. Transport – fuels 5. Medical care

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5

6

7

8

1. No running in the laboratory

2. Long hair should be tied in the laboratory

3. No eating in the laboratory

4. Reagents must be stoppered

5. Flammable reagents should be kept away

from Bunsen flame6. Safety goggles should be used

7. No playing in the laboratory

8. Unattended Bunsen flame

A. Physical change- NO NEW substance formed. e.g. boiling, melting, colour etc.

solid gas

liquid

melting

freezingbo

iling

cond

ensa

tion

sublimation

B. Chemical change- NEW substance formed. e.g. rusting of iron. (iron iron oxide)

(rust)

Q. 1.4

(a) magnesium magnesium oxide

(b) sugar sugar solution

(c) water ice

(d) iron iron oxide

Solution

chemical

physical

physical

chemical

C. Physical properties

- properties that can be determined without the substance changing into another substance.e.g. solubility, electrical/thermal conductivity, malleability, ductility

D. Chemical properties

- chemical reactions of the substance. (NEW substances formed after reaction.)e.g. chemical properties of sodium1. Reacts with air 2. Reacts with water

Particles

tiny pieces of matter that make up everythingDiffusion- spreading and mixing of one substance into another, from a place of higher concentration to a place of lower concentration e.g. perfume, iodine in alcohol

Solution – a homogeneous mixture of two or more substancesSaturated Solution – the solvent has dissolved the max. amount of the solute it can at that temperature

Kinetic Theory of Matter1. All matter is composed of tiny particles,

with spaces between them.

2. (a) Particles are in constant, random motion.

(b) Average K.E. of particles with temp.

Solid

1. Tightly packed with little spaces2. Fixed volume and shape,

incompressible3. Vibrate about their fixed

positions

Liquid

1. Fairly close packed 2. Fixed volume but no fixed shape3. Particles can move freely, not

arranged in a fixed pattern

Gas

1. Widely separated with a lot of spaces

2. No fixed volume and shape, easy to compress

3. Move freely at great speeds

A. Element- pure substance which cannot be broken down into anything simpler by chemical methods.e.g. copper (Cu), hydrogenB. Compound- two or more elements chemically joined together. e.g. water (H2O), carbon dioxide (CO2)

Most abundant elements :

1. Oxygen (oxygen gas, water, sand)

2. Silicon (sand - silicon dioxide SiO2)

3. Aluminium

Q 2.4

(a) Phosphorus (e) Sulphuric acid

(b) Sodium chloride (f) Mercury

(c) Ammonia

(d) Glucose

Element

Compound

Compound

Compound

Compound

ElementNaCl

NH3

C6H12O6

H2SO4

Word equationcopper + chlorine copper chloride

reactants

product

carbon + oxygen carbon dioxide

hydrogen + oxygen water

Q. 2.5

Properties of compounds compare with constituent elements

+

silvery grey solid

greenish yellow gas

white solid

Mixture – two or more substances which have NOT chemically combined togetherelement/element mixture

alloys

element/compound mixture

air, oxygen in water

compound/compound mixture

sea water

Q.2.7

Five elements :

Five compounds :

Five mixtures :

Q.14-17 (P.46)

A B C D

Pure element :Pure compound :Mixture of elements :Mixture of compounds :

CB

DA

Structure of Earth

Crust, mantle, outer core and inner core

Atmosphere, oceans and Earth’s crust

Atmosphere – gaseous layer surrounding the

EarthAir – gaseous mixture making up atmosphere

Q3.2 : The Earth’s core consists of iron, which is magnetic.

Composition of air- a mixture contains 21% O2, 78% N2, traces of CO2, water vapour and noble gases (helium, neon ….).

syringe Bsyringe Acopper turnings

Strong heat

copper + oxygen copper oxide(reddish brown) (black)

air

Initial volume = 100Final volume = 79Volume of oxygen used 100 – 79 = 21 cm3

Assumptions :

1.Assume the reaction between copper and

oxygen is complete.2. Assume oxygen is the only

reactive gas in air.

3. Assume oxygen content is the same everywhere.

Separation of O2 and N2- by fractional distillation of liquid air

alcoholwater(100 ºC) + alcohol (78 ºC) heat

coldwater

Thermometer

alcohol vapour

Simple distillation

Compression and

cooling chamber

air in

liquid air(- 200C)

Fractionating column

temp.

O2(g)(-

183C)N2(g)

(- 196C)

TEST FOR O2 - relights a glowing splint.

growing splint

TEST FOR H2 - ‘pop’ sound test

- use a burning splint, ‘pop’ sound is heard.

Uses of gases

A.Oxygen

- breathing.

- rockets and space shuttles.

B. Nitrogen

- provide inert atmosphere.

- refrigerant.

- making ammonia.

C. Carbon dioxide- refrigerant.

- soft drinks.

- fire extinguishers.

D. Noble gases- airships, advertising signs, light bulbs.

1.2 The Ocean

A. Solvent, Solute and Solution

Perfume - flower extracts dissolved in alcohol.Correction fluid - plastic dissolved in 1,1,1-trichloroethane.Iodine tincture - iodine in alcohol.

Solute + Solvent Solution(sugar + water sugar solution)

1.2.2 Composition of sea water- common salt / table salt (NaCl), pure H2O.Extraction of NaCl and isolation of pure H2OA. Evaporation

- salt is remained. (Water CANNOT be collected.)

- separate soluble solid from solution.

Advantage : quick and simple.

Disadvantage : solid obtained only which contains impurities.

B. Crystallization(i). Heat the solution until it is saturated.(ii). Cool rapidly to obtain a small crystal or cool slowly to obtain a large crystal.

OR By seeding.glass rod

saturated solution

purecrystal

(iii). Filter to obtain the crystals.

(iv) Wash the crystal with distilled water.

(v) Dry the crystal with a filter paper.

Advantage : pure crystal can be

obtained.Disadvantage : time-consuming

- separate soluble solid from solution.

C. Distillation

to provide smooth boiling

- pure solvent (water) obtained.- separate solvent from a solution. (two miscible liquids with different b.p.)

Advantage : pure liquid obtained.

Disadvantage : complicated set-up.

D. Filtration

- separate insoluble solid.

Advantage : quick and simple.

Disadvantage : rough separation.

Test for sodium and chlorine in common salt

Flame Test

- test for sodium

Materials used : platinum (Nichrome) wire, conc. HCl, a bunsen burner.1. Platinum wire is washed with conc. HCl and placed in a bunsen flame to observe the flame colour.2. Repeat the above procedure until the flame colour is illuminous.3. Bring the platinum wire into contact with the solid sample so that some of the sample adheres to the wire, hold the wire in the edge of a illuminous bunsen flame.

Element in compound

Flame coloursodium golden yellow

potassium lilac(purple)calcium brick red

Silver nitrate (AgNO3) Test

- test for chlorine

1. The sample is dissolved in water.2. Excess dil.HNO3 is added into the sample solution to remove carbonate, oxide. (Basic substances)AgNO3 also forms precipitate with carbonate/oxide.3. AgNO3(aq) is added.4. White ppt. (AgCl) is observed to show the presence of Cl-.AgNO3(aq) + NaCl(aq) AgCl(s) + NaNO3(aq)

Test for water

- cobalt (II) chloride paper is used.

- from blue to pink.

Electrolysis of sea water and uses of the products

NaOH remainedCarbon electrode

Cl2(g) H2(g)

Sea water

1. Mixed with Cl2 to form bleach

2. Making soap, detergents

sodium hydroxide (NaOH)

1. Sterilize drinking, swimming pool water2. Making plastics(P.V.C.)chlorine

1. As rocket fuel2. Making ammonia (NH3)

hydrogenUsesProducts

1.3 Rocks and Minerals

rocks as a source of minerals

Minerals - individual chemical compounds that make up rocks

- metal ores contained.

Extraction of metals from their ores

A. Heating metal oxides

e.g. 2Ag2O 4Ag + O2

B. Heating metal oxides with carbon

e.g. ZnO + C Zn + COC. Electrolysis of molten ores

electrolysise.g. 2Al2O3 4Al + 3O2

Investigation of Calcium carbonate

- in 3 forms : limestone, chalk and marble.

A. Action of Heat

quicklimeCaCO3 CaO + CO2

- when water is added into CaO.

slaked lime slightly soluble in H2O

CaO + H2O Ca(OH)2(s) lime water

B. Action of Water- CaCO3 is insoluble in water.

C. Action of Acids

CaCO3 + HCl CaCl2 + CO2(g) + H2OEffervescence(Bubbles given)

D. Erosion processes in nature- major causes of erosion are gravity, running water, waves ice and wind.

CO2 + H2O H2CO3 carbonic acid

soluble

H2CO3 + CaCO3 Ca(HCO3)2

- CO2 is tested by lime water.Ca(OH)2(aq) + CO2(g) CaCO3(s) milky / white ppt.

Thermal decomposition of CaCO3

CaCO3 CaO + CO2

Test for calcium and carbonate ion

- Ca is tested by flame test.- CO3

2- is tested by heating the sample and then test the presence of CO2.

Or by adding dilute HCl and test the presence of CO2.