1. THE STRUCTURE OF
THE ATOM
Chapter 2

2. In this chapter, you will learn to:
Analyse matter
Synthesise the atomic structure
Understanding isotopes and their uses
Understanding the electronic structure of an atom
Appreciate the orderliness and uniqueness of the atomic
structure.

3. 2.1 ANALYSING MATTER
Describe the particulate nature of matter
Define atoms, molecules and ions
State the kinetic theory of matter
Relate the change in the state of matter to the change in heat.
Relate the change in heat to the change in kinetic energy of
particles.
Explain the inter-conversion of the states of matter in terms of
kinetic theory of matter.

4. A) Particulate Nature of Matter
Matter refers to any substance which has mass and occupies
space.

5. Continue…
According to the particulate theory of matter, matter is made
up of tiny and discrete particles.

6. Continue…
Matter is composed of particles which consist of atoms,
molecules or ions.
Matter can exist in three different phases. These phase
include solid, liquid and gas.

7. B) Atoms, Molecules and Ions

8. Atoms
An atom is the smallest neutral particle in an element and it
can exist by itself or take part in a chemical reaction.
Example:
 Copper, Cu, atom is a neutral particle.
 The smallest particle in oxygen gas is the oxygen, O, atom.
 Copper can exist by itself as copper atoms making up copper
metal or combine with oxygen atoms to form copper(II) oxide,
CuO, through a chemical reaction. Oxygen
Oxygen Copper
atom atom atom
Copper atoms Oxygen gas copper(II) oxide

9. Molecules
Molecules are neutral particles, made up of two or more
atoms of the same element or different elements.
Example:
 Oxygen gas comprises oxygen molecules, O2. each molecules is
made up of 2 oxygen atoms.
 Copper(II) oxide, CuO, consist of two different atoms, Cu and O.
Oxygen
Copper Oxygen
atom
atom atom
Oxygen gas Copper(II) oxide

10. Others Molecules
H2 H2O NH3 CH4

11. Ions
Ions are particles which are positively or negatively charged.
They are produced when atoms or a group of atoms receive or
donate electrons.
Positively-charged ions are called cation, while negatively-
charged particles are called anions.
The ionic compound NaCl

12. Continue…
cation – ion with a positive charge
If a neutral atom loses one or more electrons
it becomes a cation.
Na 11 protons 11 protons
Na+
11 electrons 10 electrons
anion – ion with a negative charge
If a neutral atom gains one or more electrons
it becomes an anion.
Cl 17 protons 17 protons
Cl-
17 electrons 18 electrons

13. C) The Kinetic Theory of Matter
The kinetic theory of matter state that matter consists of tiny
and discrete particles that are constantly moving.
This theory has three basic assumptions:
 Matter is composed of small particles. These molecules move in
random motion and collide with one another.
 There are attractive forces between the molecules when they are
close together.
 Movements of the particles is affected by heat.

14. D) Change in the state of matter
STATE SOLID LIQUID GAS
Not compact. Loosely
arranged with larger Particles not arranged
Compact and orderly with small
Arrangement spaces between in order. Very far apart
empty spaces between
of particles particles which are in with large empty
particles.
contact with one spaces.
another.
Vibrate, rotate and
Vibrate, rotate and
Vibrate and rotate at their fixed move from one point
Movement of move very freely and at
positions. Cannot be to another more freely
particles random. Compressed
compressed. than solid particles.
very easily.
Cannot be compressed.
Forces of
Fairly strong but
attraction
Very strong weaker than solid Very weak
among
particles.
particles
Higher energy content Highest energy content
Low energy content as
Energy content as particles can move as movement is at
movement is restricted.
easily. random

15. Continue…
 When a substances is
heated or cooled its physical
state alters with a
corresponding change in
energy:
 During melting,
evaporation/boiling and
sublimation, heat is
absorbed by substances. In
all these physical process,
temperature rises.
 During freezing,
condensation and
sublimation, heat energy is
released and temperature
drops.

16. Heating graphs of substance
Temperature/ oC
Boiling
point
Melting
point

17. Temperature/ oC
Boiling
point
Freezing
point

18. E) Diffusion
• Is the movement of particles at random from a highly
concentrated area to less concentrated area.