States of Matter, Changes of State, and Particle Theory (Video Notes)

Vocabulary flashcards covering solids, liquids, gases, changes of state (melting, freezing, evaporation, condensation, boiling), diffusion, and basic particle concepts (atoms, molecules, ions).

solid

A state of matter with a fixed shape and fixed volume; it does not flow and cannot be easily compressed.

liquid

A state of matter with fixed volume but a shape that takes the container; it flows easily.

gas

A state of matter with no fixed shape or volume; it expands to fill its container and is lighter than the same volume of solid or liquid.

melting

The change of state from solid to liquid when heated.

melting point

The temperature at which a solid changes into a liquid (e.g., 0°C for ice).

freezing

The change of state from liquid to solid when cooled.

freezing point

The temperature at which a liquid becomes a solid (e.g., 0°C for water).

evaporation

The change from liquid to gas that occurs below the boiling point; can happen when a liquid is heated.

boiling

Rapid evaporation of a liquid at its boiling point, forming steam.

boiling point

The temperature at which a liquid boils (e.g., 100°C for water).

condensation

The change from gas to liquid; the opposite of evaporation.

diffusion

The spreading of particles through a medium due to collisions, moving from high to low concentration; occurs in liquids and gases.

atom

The smallest unit of an element; the basic building block of matter; some substances have single atoms as particles (e.g., argon in air).

molecule

A group of two or more atoms bonded together; water and bromine are molecules; air is made of molecules of nitrogen and oxygen.

ion

A charged particle (atom or group of atoms) that carries a net electric charge (e.g., potassium manganate(VII) ions).

particle

A tiny piece of matter; the term used for atoms, molecules, or ions that make up substances.

Brownian motion

The random, jiggling movement of particles suspended in a fluid, observed by Brown; evidence that matter is made of particles.

electron microscope

An instrument that images atoms using beams of electrons rather than light.

room temperature

A standard temperature used in these notes, taken as 20°C.

oxygen at room temperature

Oxygen is a gas at room temperature (20°C).

iron at room temperature

Iron is a solid at room temperature and is used in building structures.

mercury at room temperature

Mercury is a liquid at room temperature.

water (three states)

Water can exist as ice (solid), liquid water, and steam (gas); these states change with heating or cooling.