Unit 3: Thermal Energy and Phase Changes

Vocabulary flashcards covering thermal energy, thermal conductivity, phase changes, and density data analysis from Unit 3.

Thermal Energy

The total kinetic (movement) energy of the particles that make up a substance.

Temperature

A measure of the average kinetic energy of the particles in a substance (how hot or cold something is).

Thermal Conductivity

A measure of how quickly heat energy flows through a specific material.

Thermal Conductor

A material that easily allows heat to pass through it quickly (e.g., metals like copper or aluminum).

Thermal Insulator

A material that slows down or resists the transfer of heat (e.g., styrofoam, wood, air).

Thermal Radiation

Energy transferred by electromagnetic waves (like infrared light) that can travel through empty space.

Absorption

The process of taking in thermal radiation or heat energy.

Emission

The process of giving off or releasing thermal radiation into the surroundings.

Thermal Equilibrium

The state where two objects or a system and its environment reach the same temperature, meaning heat is absorbed and emitted at the exact same rate.

Kinetic Energy (Particles)

The energy of motion of particles; higher kinetic energy means particles move faster, which raises the temperature.

Potential Energy (Particles)

The stored energy related to the distance and position between particles.

Phase Change

A physical change from one state of matter (solid, liquid, gas) to another without changing the chemical identity.

Heating/Cooling Curve

A graph showing how temperature changes over time as thermal energy is added to or removed from a substance.

Endothermic Process

A process or phase change that absorbs heat energy from its surroundings (e.g., melting, boiling).

Exothermic Process

A process or phase change that releases heat energy into its surroundings (e.g., freezing, condensing).

Intermolecular Forces (Attractive Forces)

The forces of attraction that pull particles toward each other.

Thermal Expansion

The increase in the volume of a substance when heated, caused by particles moving faster and spreading farther apart.

Density

The amount of mass contained in a given volume of a substance ($D = \frac{m}{V}$).

Mass

The amount of matter in an object, usually measured in grams ($g$).

Volume

The amount of space an object or substance takes up, usually measured in cubic centimeters ($cm^3$) or milliliters ($mL$).

Slope (on a Mass vs. Volume Graph)

The steepness of the line on a mass vs. volume graph, which represents the density of the substance ($\frac{\text{rise}}{\text{run}} = \frac{\text{mass}}{\text{volume}}$).