States of matter y9

Density

The mass in a given volume of a substance (solids are denser than liquids, which are

denser than gases)

Temperature

The measure of the average kinetic energy of the particles in a substance

Melting

is the process where a solid turns into a liquid as it absorbs heat, resulting in increased particle movement.

Melting point

the specific temperature at which a solid transitions to a liquid. (ice melts at 0°C)

Boiling

The change of state from a liquid to gas, due to an increase in temperature (also called vaporisation)

Condensing

The change of state from a gas to a liquid, due to a decrease in temperature

Freezing

The change of state from a liquid to a solid, due to a decrease in temperature

Sublimation

The process by which a solid turns into a gas without melting (at normal pressure)

Deposition

The process by which a gas turns into a solid without condensing (also called de-sublimation)

Evaporation

The change of state from a liquid to a gas over a range of temperatures. Evaporation happens at the surface of a liquid

Solvent

The liquid in which a solute will dissolve

Solute

The soluble substance that dissolves in the liquid to form a solution

Solution

The mixture formed when a solute dissolves in a solvent

Saturated solution

A solution with the maximum amount of solute dissolved in solvent at a particular temperature

Solubility

The maximum amount of solute (in grams) that can be dissolved in 100g of solvent (100cm3 of water) at a particular temperature.

How is Evaporation is different to boiling?

The average kinetic energy of particles will vary in a sample, hence at a particular temperature some particles will have an energy higher than the average kinetic energy, some lower

• Very fast particles at the surface of the substance have enough kinetic energy to overcome the forces of attraction between the particles and so turn to a gas (they evaporate)

• As more particles evaporate, the average kinetic energy of the sample decreases, so the temperature also decreases

• Evaporation occurs over a range of temperatures at the surface of a liquid; boiling occurs at a specific temperature throughout he whole of the liquid

Properties of a solid

Arrangement of particles : Packed closely together, all touching in a regular repeating pattern of ordered rows

Movement of particles: Vibrate around a fixed position

Kinetic energy of particles : Lowest

Forces between particles: Strong forces of attraction holding particles together

Shape, volume and density: Fixed shape and fixed volume; most dense

Properties of a liquid

Arrangement of particles : Fills from the bottom, close together, touching, some gaps between particles, randomly arranged

Movement of particles: Particles can move past each other; medium speed

Kinetic energy of particles : Higher

Forces between particles: Forces of attraction less effective than in solid, but still present

Shape, volume and density: No fixed shaped but fixed volume; less dense

Properties of a Gas

Arrangement of particles : Far apart, large spaces between particles, irregular and random arrangement

Movement of particles: Random movement at high speed in all directions

Kinetic energy of particles : Highest

Forces between particles: Negligible forces of attraction

Shape, volume and density: No fixed shape or volume; least dense

Endothermic

Processes that need energy (take in energy from the The kinetic energy of the surroundings)

The kinetic energy of the particles is increased. These processes are melting, boiling/evaporation and sublimation.

Exothermic

Processes that give out energy (release energy to the

surroundings)

The kinetic energy of the particles is decreased. These processes are condensing, freezing and deposition.

Changes of state graph

The physical state of a substance at a given temperature (solid)

If the given temperature is below the melting point of the substance, the substance is a solid

The physical state of a substance at a given temperature (liquid)

If the given temperature is between the melting and boiling point of the substance, the substance is a liquid

The physical state of a substance at a given temperature (Gas)

If the given temperature is above the boiling point of the substance, the substance is a gas

Diffusion

The spreading out (random movement) of particles from an area of

high concentration to an area of low concentration