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Chapter 4

Matter and Substances

4.1 Changes In Matter
Kinetic Theory of Matter
The theory states that:
 Matter is made up of tiny and discrete
particles
 The particles are always moving in
random motion
 The moving energy is called the
kinetic energy of particles
 The kinetic energy of particles
depends on the temperature of matter

States of Matter

Changes in state of matter Sublimation Sublimation .

2 Structure of atom 1. electron and neutron. neutral/ no charged) . negatively charged) (p. There are three types of subatomic particles: proton.4. Every substances is made up of atoms. positively charged) (n. 2. (e.

4. Aluminium (Al) Proton number 13 (always smaller number) Name of element Nucleon number 27 Al . The number of nucleon = neutrons number + proton number • Symbol of element. For example. Nucleon number is the total number of protons and neutrons in an atom.3 Proton number and Nucleon number Proton number is the number of proton in an atom.

How to determine the charges of particles Particles Number Number of of protons electrons A 6 8 B 10 9 C 11 11 a) Positively charged particles: B ( more proton number) b) Negatively charged particles: A (more electron numbe c) Particle that has no charge (neutral): C (proton = elect .

Isotopes Isotopes of certain elements contains the same number of protons but a different number of neutrons in their atoms. hydrogen . For example.

4 Periodic table •Elements are arranged according to their proton number (increases) •Divided into metals.4. non-metals and semimetals •Elements in the same group have same chemical properties .

Can be used to forecast the properties and uses of particular element. .Importance of periodic table Helps us to determine the properties of elements.

5 Properties of ATOMS Substances MOLECULES IONS •Substances made Substance made up •Substance made up up of atoms only. •The smallest (two or more •Contain charged particle. 4. liquid or gas •In solid mercury) •Cannot conduct •Cannot conduct •Conduct electricity electricity electricity except in •High boiling/melting •Low boiling/melting molten or aqueous point point states ALUMINIUM •High boiling/melting point Oxygen gas Water Aluminiu Sodium chloride (NaCl) m . particle •In solid (except •In solid. of molecules only of ions only. atoms).

molecules and ions Section A: Melting Substanc Type of Melting es substanc point point. Physical properties of substance made up of atoms. e Lead ATOM High Sulphur MOLECULE Low Lead/sulphur/ Lead (II) ION High Lead(II)bromide Bromide •High melting point = strong forces of attraction •Low melting point = weak forces of attraction .

ions cannot move freely •Conducts electricity in molten because .Section B: Electrical conductivity SUBSTANCE ELECTRICAL CONDUCTIVITY SOLID MOLTEN LEAD Can Can SULPHUR Cannot Cannot LEAD(II)BROMI Cannot Can DE For ionic substance. lead(II)bromide: •Does not conduct electricity in solid becau .ions can move freely .

4.6 Properties of Metals and Non- Metals A) Surface condition Metals: copper Dull Shiny surface Non-metals: carbon .

B) Malleability •Non-metal: Brittle • the lump of carbon shatter •Metal :Malleable • iron wire changes shape .

C) Tensile strength Nichrome (metal) needed more weights to break Nichrome/ nylon Nylon (non- metal) needed less weight to break Metals have higher tensile strength than non-metals .

D) Electrical conductivity * Metals: the * Non-metals: bulb lights up the bulb does with copper rod not lights up * METALS with glass rod conduct * NON-METALS electricity do not conduct electricity .

E) Heat conductivity Type of Exampl Time materia e taken for ls the thumbtac k to drop off/secon ds METALS Copper 96 rod NON. Glass 130 METALS rod •Metals: copper rod are good heat conductors •Non-metals: glass rod are poor heat conductors .

4.6 Properties of Metals and Non- Metals Comparison between metals and non- metals METALS Physical properties NON-METALS Shiny Surface Dull Ductile Ductility Non-ductile/ brittle Malleable Malleability Non-malleable High Melting and Boiling Low point Good Electrical Non-conductive conductivity except carbon Good Heat conductivity Poor High Tensile strenght Low .

Uses of metals Iron is used in making cars Copper is used to make wires Silver is Aluminium is often used used to make to make power lines jewellery .

Uses of non-metals Sulphur is used to make matchstic k tips Diamonds are mostly used to Sulphur is make ingredient in jewellery making paint .

7 Purification of Substances 1. Pure substances have fixed boiling and melting point.for example.for example. 4. .do not have any impurities . * pure water boils at 100°C . Pure substances are substances that contain only one type of substance. . * pure sugar only contains sugar molecules * pure water only contains water molecules 2.

water will be boil at a temperature higher than 100°C . .Effect of impurities on the boiling point of a pure liquid The presence of impurities in a pure substance can a) increase its boiling point b) decrease its freezing point • For example.when a salt is added to pure water.

Bunsen burner. table salt Apparatus: 100cm³beaker. tripod stand. thermomater . wire gauze. Hypothesis: The presence of salt increases the boiling point of a pure liquid Variables: manipulated variable : responding variable : constant variable : Materials: distilled water.Title: Effect of impurities on the boiling point of a pure liquid (PEKA) Aim: To study the effect of impurities on the boiling point.

2. The water was heated until its boils. 4. The boiling point of the mixture . The temperature was Distilled recorded. water 3. Procedure: 1. Two spatulas of table salt were added into the distilled water and the mixture was heated again. Distilled water was filled into a Salt beaker until it is half full.

Results :The presence of Boiling point of table salt distilled water (°C) Absent 100 Present • Analysis: • Conclusion: .

Methods of purification Purification is a process of removing impurities from a substance. The methods are: a) Filtration: process of separating solid from liquid Mixture of solid and liquid Filter paper Residue (solid) Filtrate (liquid) .

production of salt from sea water .production of pure solid copper(II)sulphate from its solution Substance in crystal form .b) Crystallisation : process of forming crystals from a liquid or gas .

petroleum fractions (fractional distillation) Tap water flows to cool the vapour and condense it into liquid To make sure the condenser is fully filled with water Porcelin chips: To break up the air bubbles . . c) Distillation: a process to obtain a pure liquid from a solution of liquid mixture.production of distilled water .

Fractional distillation .

With scientific knowledge and technology. humans have used the properties of substances to make their lives better. For example. . pure metals which may not be suitable for a particular purpose because they are too heavy or rust easily. . 4.pure iron steel (strong and does not rust) .they can be processed into more suitable substances.8 Uses of various substances Humans need various types of substances in daily life.

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