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


⇲ For exercise(objective and subjective), download for free on Android OS.