1

CHAPTER 4 MATTER AND SUBSTANCE

1.1 Analysing changes in the states of matter1.2 Understanding the structure of an atom1.3 Applying the idea of proton number and nucleon number in atoms of

elements1.4 Understanding the classification of elements in the Periodic Table1.5 Understanding the properties of substances based on the particles

present in them1.6 Understanding the properties and uses of metals and non-metals1.7 Analysing methods of purifying substances1.8 Appreciating the existence and uses of various substances of

different characteristics

4.1 Analysing Changes in the States of Matter

Kinetic Theory of Matter

1. Matter is anything that ________________________________________________

2. The kinetic theory of matter states that...

a) matter is made up of _______________________________________________

b) the particles are constantly ___________________________________________________

c) there are _________________________________________________________________

d) particles have _____________________________________________________________

e) as the temperature increases _________________________________________________

The Characteristics of Matter in the Solid, Liquid and Gas StatesCharacteristics Solid Liquid Gas

Arrangement of the

particles

Movement of the particles

Forces of attraction

between the particles

Kinetic energy of the

particles

Density

Shape

Volume

Examples

2

Changes in the State of Matter

3

4.2 Understanding the structure of an atom

Atomic Structure

We know that matter consists of ____________________________________. The particles are

known as ___________ An atom is made up of ______________________________________

__________________________________

Development of the Atomic Model

• 1808, John Dalton - Dalton's atomic theory

• 1897, Joseph John Thomson - Discovered electrons

• 1911, Rutherford - Discovered the nucleus

• 1932, Sir James Chadwick - Discovered neutrons

Subatomic Particles- Proton, Neutrons and Electrons

1. There are three types of subatomic particles in an atom, i.e. protons, neutrons and electrons.

2. __________________________ make up the _____________________ in the centre.

3. ___________ circle around the nucleus at a _________________________called

___________

4. The properties of subatomic particles are compared in the table below.

Properties Electrons Protons Neutrons

Location

The Movement

Charge

Relative mass

The actual mass

Symbol

4

4.3 Applying the idea of proton number and nucleon number in atoms of elements

Proton Number and Nucleon Number in Atoms

Proton Number

Nucleon Number

1. The atomic mass _________________________________________________________ in the

atomic nucleus as _____________________________________________________________

2. For an element, X, the proton number and nucleon number can be represented.

The table below shows a few examples of elements with their proton numbers and nucleon

numbers.

ElementNuclide

notation

Nucleon

number (A)

Proton

number (Z)

Number of

electrons

(=Z)

Number of

neutrons

(A - Z = N)

Hydrogen H11

Helium He24

Lithium Li37

Chlorine Cl1735

Isotope

5

1. Isotopes are __________________________________________________________________

__________________________________

2. Isotopes of the same element have _______________________________________________

_____________________

3. Oxygen has three isotopes, __________________________________. The proton number is

____but the three isotopes _____________________________________

4. The diagram below shows the isotopes of hydrogen.

Exercises 4.3

4.4 Understanding the classification of elements in the Periodic Table

6

1.

All the elements must be classified and arranged in a proper way. Scientists have arranged these

elements based on their physical properties and chemical properties. Dmitri Mendeleev

(father of the periodic table") had classified the elements according to ascending order of

atomic mass.

The Groups and Periods in the Periodic Table

1. The periodic table has ____________ All the elements in each group have the _____________

___________they have _________________________________________________________

2. The ________________ in the periodic table are known as ________. There are ___________

in the periodic table and the element of each period is arranged in _______________________

_______________________________________

3. All elements that are in the ____________________ have the __________________________

_______________________________________

The Importance of the Periodic Table

The ________ in the_____________ can be divided into ________________________ namely

_______________________________________

• When ________________________________, the elements vary.

1. ________________________ - the elements change from __________________________

2. _____________ condition - the elements change from the ___________________________

3. Elements also change from being ____________________________________________

4. _______________________________

Exercises 4.4

7

Structured Question1. Diagram 6 shows an incomplete periodic table.

(a) Among the elements represented by the letters U, V, W, X, Y and Z, state one element which

(i) is a metal: __________________________________________________________________[1 mark]

(ii) a non-metal: ________________________________________________________________[1 mark]

(iii) a transition element:__________________________________________________________[1 mark]

(b) State one similarity between elements Y and Z.

____________________________________________________________________________________[1 mark]

(c) Which element has a proton number of 32?

____________________________________________________________________________________[1 mark]

(d) The atom of element Y has 20 neutrons in its nucleus. What is its nucleon number?

____________________________________________________________________________________[1 mark]

2. Diagram 7 shows several examples of metals from a group in the Periodic Table.

Explain how you would develop a concept based on the information given in the diagram. Your explanation should be based on the following criteria:(a) Identify two common characteristics.

______________________________________________________________________________________________________________________________________________________

[2 marks](b) Develop an initial concept.

___________________________________________________________________________[1 mark]

(c) Give other examples of elements in the same group. Give examples of elements with similar properties but belong to a different group.

______________________________________________________________________________________________________________________________________________________

[2 marks]

(d) Explain the actual concept.

___________________________________________________________________________

[1 mark]

8

4.5 Understanding the properties of substances based on the particles present in them

Matter consists of particles known as atoms. Elements are substances that consist of atoms of

one type only. Metals are substances made up of atoms held in place by strong forces of

attraction called metallic bonds. Most non-metals form molecules; a molecule consists of two

or more atoms of the same type or of different types which are chemically combined together.

Some metals combine with non-metals by transfer of electrons to form ionic compounds.

Atom

1. An atom is the smallest particle of an element.

2. Most metals are made up of atoms of one type only and can exist on

their own.

3. Atoms in metals are held by very stronq forces of attraction called

metallic bonds.

Molecules

1. A molecule is a particle that is made up of two or more atoms that are combined

chemically.

2. There are two types of molecules:

a) molecules that have two or more atoms of the same type.

Examples: nitrogen molecules and oxygen molecules

b) molecules that consist of two or more types of atoms.

Example: ammonia molecules and water molecules

3. There are weak forces of attraction between the molecules which are known as Van der

Waals forces.

4. There is a group of solids known as covalent macromolecules which are held by very

strong covalent bonds . Diamond and graphite are the best examples of covalent

macromolecules which are strong solids.

9

ions

1. Atoms that lose electrons will become positively charged ions, while atoms that accept

electrons will become negatively charged ions.

2. When sodium (a metal) reacts with chlorine (a non-metal) to form compound, the sodium atoms

lose electrons to become positively charged ions, Na + . and chlorine atoms accept

electrons to become negative ions. CI -

3. The ions are very stable and have strong electrostatic forces of attraction and have high

melting and boiling points.

Physical Properties

10

Exercises 4.5

Essay Question

You are given lead, sulphur and lead(II) bromide (all in powdered form).(a) Suggest a hypothesis to investigate the above statement.

___________________________________________________________________________ [1 mark]

(b) Describe an experiment to test your hypothesis based on the following criteria.(i) Aim of the experiment [1 mark](ii) Identification of variables [2 marks](iii) List of apparatus and materials [1 mark](iv) Procedure or method [4 marks](v) Tabulation of data [1 mark]

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

11

The electrical conductivity of substances made of atoms, substances made of molecules and substances made of ions are different.

___________________________________________________________________________

___________________________________________________________________________

4.6 Understanding the properties and uses of metals and non-metals

There are many objects that are made of metals. What are these objects? Examples are screws,

wrenches, keys, nails, and many more. What about non-metallic objects? Examples of non-metals

are paper, books, wooden desks, plastic cups and others.

The Properties and Uses of Metals and Non-metals

12

Uses of Metal

13

Uses of Non-metal

14

Non Metal Physical property and useCarbon Carbon exists in two forms of solid: diamond and graphite

(a) Diamond(i) Natural carbon is very hard. The carbon atoms in diamonds are bonded

together using strong covalent bonds in a giant structure as shown in the figure below.

(ii) Uses: • acts as a drilling bit for cutting stones and glass • serves as expensive and beautiful jewellery

(b) Graphite(i) Graphite consists of layers of carbon atoms strongly bonded in the form of

hexagonal rings.(ii) The layers of carbon are, however, weakly bonded to each other. As a

result, they can move easily over one another.(iii) Graphite can conduct electricity.(iv) Uses:

• serves as a lubricant in machines• for making pencil lead• acts as a carbon electrode in a dry cell

Clorine (a) Chlorine is a poisonous gas which is yellowish green in colour.(b) It dissolves easily in water to form hydrochloric acid and hypochlorous acid.(c) Uses:

(i) serves as a bleaching agent in detergents and in the paper industry(ii) for making organic solvents like chloroform and tetrachloromethane(iii) kills germs and cleans water in swimming pools and water purification

Sulphur (a) Sulphur is yellow in colour and burns easily.(b) Uses:

(i) for making sulphuric acid, paints and detergents(ii) for making anti-fungal drugs, synthetic fibres and matches(iii) added to natural rubber to produce vulcanised rubber(iv) for making solvents like carbon disulphide

Noble gas (a) Uses:(i) Argon — for filling light bulbs(ii) Neon — for filling advertising lamps and electronic appliances(iii) Helium — for filling balloons(iv) Krypton - to give out light of high intensity in light bulbs(v) Xenon — for making anaesthetic drugs

Exercises 4.6

15

4.7 Analysing methods of purifying substances

16

Pure Substances

1. Pure substances contain atoms or molecules of only one type.

2. Pure substances have fixed melting and boiling points.

3. The presence of impurities will lower the melting point but increase the boiling point of a

substance.

4. The melting point of ice is 0°C. The presence of impurities (e.g. salt) will lower the melting

point by a few degrees depending on the quantity of salt added (possibly -2°C or -3°C).

5. Purified distilled water boils at 100°C The presence of impurities (e.g. salt) will increase the

boiling point (probably 102°C or 103°C).

Methods of Purification

1. Impurities can be separated physically by the process of filtration, distillation and

crystallization.

2. How do you separate a mixture of sugar and sand?

The mixture of sugar and sand is added with water so that all the sugar dissolves. Then

the mixture is filtered. The insoluble sand will be left on the filter paper, and the filtrate

(sugar solution) is collected. This process is called filtration. The sugar solution is then

heated until it is saturated. Then the solution is left to cool and sugar crystals are

formed. This process is called crystallization.

3. How do you get pure water from sea water?

Sea water is heated to boiling at 100°C, the water vapour condenses in the Liebig

condenser and is collected. The water that condenses is known as the distillate (purified

distilled water). This process is called distillation.

4. When we want to separate a mixture of two liquids such as water and alcohol or petroleum

components, fractional distillation can be carried out.

Application of the Method of Purification

17

Water is a necessity of life in this world. Three quarters of our world is covered with water. The

problem the world is facing now is environmental pollution that has affected the supply of clean

water for our daily use. Research has been carried out on various methods to get clean water.

Applications of Purification

The Process of Obtaining Purified Distilled Water

1. Several countries in the Middle East have been distilling sea water to get drinking water.

2. Tap water is distilled extensively to get purified distilled water (pure water).

3. Purified distilled water is used in the preparation of chemical solutions and medicines in

hospitals.

4. The water in the batteries of vehicles can also be replaced with distilled water.

The Process of Obtaining Pure Clean Alcohol

In the manufacture of alcohol, distillation is carried out to purify and increase the concentration of

the alcohol.

Fractional Distillation to Obtain Petroleum Components

The Production of Salt Crystals - Crystallization

1. Evaporation of sea water produces salt crystals.

2. Sea water is passed into a large storage and left to evaporate in the Sun.

3. After evaporation, the salt solution will be saturated, forming salt crystals

Exercises 4.5

18

Essay Question

You are given distilled water and common salt.(a) Suggest a hypothesis to investigate the above statement.

___________________________________________________________________________ [1 mark]

(b) Describe an experiment to test your hypothesis based on the following criteria.(i) Aim of the experiment [1 mark](ii) Identification of variables [2 marks](iii) List of apparatus and materials [1 mark](iv) Procedure or method [4 marks](v) Tabulation of data [1 mark]

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

19

The boiling point of water increases when some salt is added into the water.

4.8 Appreciating the existence and uses of various substances of different characteristics

Understanding the characteristics and different conditions of different types of substances allows

us to use the substances for different purposes. Imagine our lives without electricity, vehicles or

anything which will make our lives easier.

Appreciating the Existence of Substances

Water

1. Life on Earth will not exist without water.

2. Water can exist in three states, i.e. the solid (ice), liquid (water) and gas (water vapour).

3. Water is used for cooking, drinking, washing, and as a solvent.

4. Water that flows in dams can generate hydro-electric power.

Metal - /Aluminium

1. Without aluminium aircraft may still be made of wood or other materials.

2. The strength of the aluminium alloy duralumin, which is light in nature is suitable for use in the

manufacture of aircraft.

3. Aluminium is used also in the manufacture of cooking utensils such as pots and pans because

aluminium is a good conductor of heat.

4. Aluminium is a good conductor of electricity and is very suitable for use as cables for the

transmission of electricity from the power plants to our homes.

Examples of cooking utensils made from aluminium

Metal - Iron

1. Iron metal is very strong and suitable for making steel used in the construction of bridges and

buildings.

2. Iron will rust. Therefore, when using iron to make car bodies or gates, iron must be painted to

prevent rusting.

Non-Metals

1. Oxygen is essential for living things to survive.

2. Oxygen is required for combustion.

3. Petroleum is widely used as a fuel in the transportation industry and machinery in factories.

Imagine how our lives will be without petroleum today?

4. Many objects that we use today are synthetic materials made from petroleum.

20