## Wednesday, 26 November 2014

### 2.1 Matter

Matter
■ Anything that occupies space and has mass.
■ Three states of matter: Solid, liquid and gas.
■ The animation below shows the characteristics of matters in solid, liquid and gaseous states.
■ This video contains information about the characteristics of matters.
■ Particle of matters
 ► Matter is made up of very small discrete particles. ► Elementary particles that make up matter may be atoms, molecules or ions. ► The animation below shows the particle of matter classification.
■ Evidences of the existence of these particles.
 ► Ink spreads throughout the water when it drops into a beaker of water. ► Gas smell detected when the gas tap in the laboratory is opened.

Kinetic theory of matter
■ Kinetic theory of matter:
 ► The particles possess kinetic energy. They are in constant motion and constantly collide with each other. ► Particle often move randomly and the velocities of the particles in the three physical states of matter are different. ► There are forces of attraction between particles of matter. These attraction forces will increase as the distance between the particle become closer. ► The higher the temperature, the higher is the kinetic energy as the velocity of the particles increases. ► At a given temperature, the lighter particles move faster than heavier ones.
■ Evidences
 ► Diffusion: The movement of particles in matter from an area of high concentration to an area of low concentration until both areas has the same concentration. ► Brownian movement: The particles of liquid and gas move randomly and collide against one another.

 Laboratory Activity 2.1.1: Investigating the diffusion of particles in a gas, liquid and solid

The changes in the states of matter
■ Heat energy determines the movement of particles in matter:
 ► If the temperature of matter increases, kinetic energy in the particles will increase. ► The particles will move at a faster rate.
■ When heat is supplied:

The state of matter will change from solid to liquid and finally to gas.

The changes in the state of matter which take place are :
 ○ Melting – from solid state to liquid state ○ Boiling – from liquid state to gas state ○ Sublimation – from solid state to gas state (skipping the liquid state)

The animation below shows a graph on the change of temperature when heating a substance.

 ○ At A, the substance is in a solid state. ○ At AB, energy is absorbed by particles when heated. ○ At B, the substance is still solid. ○ At BC, is the melting point. ○ At C, the substance is in liquid state. ○ At CD, temperature rises causing the particles to obtain more kinetic energy. ○ At D, the substance is in liquid state ○ At DE, the substance is in a liquid-gaseous state. ○ At E, the substance is in gaseous state. ○ At EF, the particles continue to absorb heat and move faster.
■ When heat is released:

The state of matter will change from gas to liquid and finally to solid.

The changes in the state of matter which take place are :
 ○ Freezing – from liquid state to solid state ○ Condensation – from gas state to liquid state ○ Sublimation – from gas state to solid state

The animation below shows a graph on the change of temperature when cooling a substance.

 ○ At G, the substance is in gaseous state. ○ At GH, the particles loses kinetic energy. ○ At H, the substance is still in gaseous state. ○ At HI, this is the boiling point. ○ At I, the substance is in liquid state. ○ At IJ, the temperature falls and the particles begin to release energy. ○ At J, the liquid begins to freeze. ○ At JK, this is the freezing point. ○ At K, all liquid is now in solid state. ○ At KL, the temperature of the solid keeps going down.
■ The animation below shows the changes in the state of matter and the heat change.
 Laboratory Activity 2.1.2: Determining the melting point of naphthalene