Solids, Liquids & Gases

Study Notes

Kinetic Theory: All matter is composed of tiny, moving particles. These particles are in constant random motion, colliding with each other and the container walls. The energy lost during collisions is insignificant.

Solids: Particles are tightly packed in a fixed arrangement. Particles vibrate but do not move.
Liquids: Particles are close together but with no distinct arrangement. Particles can move and slide around each other.
Gases: Particles are free-floating with no distinct arrangement. Particles move and collide with each other.

Solids: Definite volume and definite shape. Particles are in a crystalline fashion.
Liquids: Definite volume, no definite shape. Particles flow around each other, influenced by gravity.
Gases: No definite volume, no definite shape. Particles constantly try to escape their container.

Thermal Energy: The total energy of a material's particles. This includes both kinetic energy (energy of motion) and potential energy (stored energy).
Temperature: A measure of the average kinetic energy of the particles in a substance. It indicates how hot or cold something is.

Melting: Solid → Liquid. The solid starts to become a liquid at the melting point. Energy is required for particle movement to increase.
Freezing: Liquid → Solid. The liquid starts to become a solid at the freezing point. The average kinetic energy decreases, and particles become fixed in position.
Vaporization: Liquid → Gas. Particles in a liquid gain enough energy to escape into a gas phase.
Evaporation: Occurs slowly at the liquid surface.
Boiling: Occurs rapidly throughout a liquid.
Condensation: Gas → Liquid. Gas particles lose energy, changing from a gas to a liquid. This is the opposite of vaporization.
Sublimation: Solid → Gas. A solid changes directly to gas without becoming a liquid. An example is dry ice.

Melting Point (MP): The point at which a solid turns into a liquid.
Heat of Fusion: The energy required to change a substance from a solid to a liquid at its melting point.
Freezing Point (FP): The point at which a liquid turns into a solid.

Sublimation: The direct change of a solid to a gas without passing through the liquid phase. Dry ice is an example.

Plasma: Matter beyond the gas phase. Plasma particles have enough energy to overcome attractive forces both between particles and within atoms. Plasma makes up most of matter between stars and in stars themselves.

Amorphous Solids: Some solids don't have a crystalline structure; their shape can change without losing solid properties. Examples include wax, tar, and silly putty.