SIMPLE KINETIC MOLECULAR MODEL OF MATTER

What is matter? Matter is anything that occupies space and has mass.

Matter is made up of tiny particles called atoms.

The tiny particles that make up matter are in constant motion.

There are 3 states of matter:

Solid

Liquid

Gas

1. SOLID A solid is any material that has a fixed shape and fixed

volume.

Its particles are held by strong forces of attraction called bonds.

The particles vibrate to and fro about their fixed positions.

Examples include:

Iron

Concrete

Wood

Glass etc.

2. LIQUID A liquid has a fixed volume but no fixed shape.

It can flow to fill up any shape.

It is also called a fluid.

The particles are loosely packed.

They vibrate vigorously that the attractions cannot hold them in fixed positions.

They can move past each other (sliding).

Examples include: Water

Hydrochloric acid

Chlorine etc.

3. GAS A gas is a material that has no fixed shape and no fixed volume.

A gas quickly fills up any space available.

A gas is also a fluid because it can move from one point to another.

The particles are spaced packed.

Particles of a gas are free to move about.

There are no forces of attraction.

Particles move at high speeds

They collide with one another and the walls of the container.

Examples include: Oxygen

Carbon dioxide

Ammonia

Hydrogen etc.

ENERGY OF PARTICLES Particles in a solid and liquid are attracted to each

other by forces of attraction. These forces provide potential energy for the particles.

Particles of matter are in constant motion. They have kinetic energy.

Gases have the highest total energy because their particles are far apart and are moving at high speeds

Potentialenergy

Kinetic energy

Total energy

Solid Lowest Lowest Lowes

Liquid Medium Medium Medium

Gas Highest Highest Highest

THERMAL ENERGY The total energy (potential + kinetic) of all the atoms

in a material is called internal energy.

The hotter the material, the faster the particles move.

Energy can be transferred from one object to another e.g. a hotter object loses heat to a colder one. This form of energy transfer is called heat.

Both internal energy and heat are called thermal energy.

TEMPERATURE An object whose particles move faster has more

thermal energy.

The faster the particles, the higher the kinetic energy, the greater the thermal energy and the hotter the object.

Temperature is related to kinetic energy of particles.

Temperature is the average kinetic energy of particles in an object.

EVAPORATION Evaporation is a process by which a liquid changes into

gas.

It happens because some particles move faster than others.

Evaporation takes place on the surface of the liquid.

Evaporation brings cooling.

Molecules or particles that have the most energy escape from the liquid.

Molecules or particles with the most energy break free from the attractive forces.

FACTORS AFFECTING THE RATE OF EVAPORATION1. TEMPERATURE- The higher the temperature, the faster the rate of evaporation

because particles gain more energy at a faster rate. 2. SURFACE AREA- A larger surface area exposes more particles. The rate of

evaporation is faster with a larger surface area.3. HUMIDITY-Humidity is the amount of moisture in the atmosphere. A higher

humidity means there is more moisture in the atmosphere and thus a slower rate of evaporation. Low humidity gives a higher rate of evaporation.

4. WIND SPEED- Blowing air carries particles on the surface of the liquid.- When wind speed is high, the rate of evaporation is high.