Science Term 3

Diffusion

The movement of particles from an area of high concentration to an area of low concentration until spread out evenly.

Expansion

The increase in volume of a substance caused by heating, which makes particles move faster and spread further apart.

Contraction

The decrease in volume of a substance caused by cooling, which makes particles move slower and get closer together.

Conduction

The transfer of heat energy through a substance by direct collisions between neighboring particles.

Convection

The transfer of heat through a fluid (liquid or gas) caused by the movement of the fluid itself.

Melting

The phase change from solid to liquid, during which particles gain thermal energy and move more freely.

Freezing

The phase change from liquid to solid, during which particles lose thermal energy, slow down, and lock into fixed positions.

Evaporation

The phase change from liquid to gas occurring at the liquid's surface as particles gain energy to escape.

Condensation

The phase change from gas to liquid, during which particles lose thermal energy and move closer together.

Sublimation

The direct phase change from solid to gas without passing through the liquid state.

Deposition

The direct phase change from gas to solid without passing through the liquid state.

Particle behavior during energy gain

Particles increase their kinetic energy, moving faster and spreading further apart.

Particle behavior during energy loss

Particles decrease their kinetic energy, moving slower and drawing closer together.

Thermal energy

The total internal kinetic energy possessed by the moving particles within a substance.

Effect of heating on particles

Supplies thermal energy, increasing the kinetic energy and motion speed of the particles.

Effect of cooling on particles

Removes thermal energy, decreasing the kinetic energy and motion speed of the particles.

States of matter capable of convection

Liquids and gases (fluids), because their particles are free to move relative to one another.

Convection current mechanism

Warmed fluid expands, becomes less dense, and rises, while cooler, denser fluid sinks to replace it.

Reason warm fluid rises

Thermal expansion causes its particles to spread apart, decreasing its overall density relative to surrounding fluid.

Reason cool fluid sinks

Thermal contraction causes its particles to draw closer together, increasing its overall density relative to surrounding fluid.

Thermal conductor

A material that allows thermal energy or electricity to transfer through it readily.

Examples of thermal conductors

Metals such as copper, aluminium, and iron.

Thermal insulator

A material that restricts or prevents the easy flow of thermal energy or electricity.

Examples of thermal insulators

Non-metal materials such as plastic, rubber, wood, and foam.

Thermal reason saucepan handles are plastic

Plastic acts as a thermal insulator, preventing heat from readily conducting to the handle and burning the user's hand.

Three primary states of matter

Solid, liquid, and gas.

Particle arrangement in a solid

Particles are tightly packed together in fixed positions and vibrate in place.

Particle arrangement in a liquid

Particles are close together but free to slide and move past each other.

Particle arrangement in a gas

Particles are widely separated and move rapidly in random directions.