Chapter 2.1

Chapter 2The Structure of the Atom

2.1 Matter

Matter: Anything that occupies space and has mass

Based on theory: Matter is made up of tiny and discrete particles. There are spaces between these particles

Types of particle:

Atoms

Molecules

Ions

Atom: The smallest particle of an element

that can participate in a chemical reaction

Molecule: A group of two or more atoms

which are chemically bonded together

Ion: A positively-charged or negatively-

charged particle

Diffusion: Occurs when particles of a

substance move in between the particles

of another substance

Diffusion of matter occurs most rapidly in

gases, slower in liquids and slowest in

solids → due to the different arrangement and movement of particles

Observe this video

Kinetic Theory of Matter

Types of matter:

Solid

Liquid

Gas

The arrangement and movement of

particles in solid, liquid and gas are

described in the kinetic theory of matter.

The Change in The State of Matter

Sublimation

Sublimation

Condensation

Boiling /

Evaporation

Melting

Freezing

When solid is heated;

The particles in the solid gain kinetic energy and vibrate more vigorously.

The particles vibrate faster as the temperature increases until the energy they gained is able to overcome the forces that hold them at their fixed positions.

At this point, the solid becomes a liquid.

This process called melting.

The temperature at which this happens is called melting point.

When liquid is heated;

The particles in the liquid gain kinetic energy and move faster.

The particles move faster as the temperature increases until the energy they gained is able to overcome the forces that hold them.

At this point, the liquid becomes a gas.

This process is called boiling.

The temperature at which this happens is called boiling point.

When liquid is cooled;

The particles in the liquid lose energy and move slower.

As the temperature decreases, the particles lose more energy until they did not have enough energy to move freely.

At this point, the liquid changes into a solid.

This process is called freezing.

The temperature at which this happens is called freezing point.

Definition:

Melting point

The temperature at which a solid changes

into a liquid at a particular pressure.

Freezing point

The temperature at which a liquid

changes into a solid at a particular

pressure.

The heating curve

Temperature (°C)

Time (min)

Melting

point

A

B C

D

solid

begin

to meltliquid

solid-liquid

The temperature remains constant because:

The heat energy absorbed is used to overcome the

force attraction between particles so that solid can

change into liquid

Heat energy is absorbed.

Particles in solid gain kinetic energy and

vibrate faster

Heat energy is absorbed.

Particles in liquid gain kinetic energy and

move faster

The cooling curve

Temperature (°C)

Time (min)

Freezing

point

E

F G

H

liquid

solid

liquid-solid

The temperature remains constant because:

The heat loss to the surrounding is equal to the

heat energy formed during particles attraction to

form a solid

Heat energy is released.

Particles in liquid lose kinetic energy

and move slower

Heat energy is released.

Particles in solid lose kinetic energy and

vibrate slower