PhET States of Matter & Kinetic Molecular Theory - Vocabulary Flashcards

Vocabulary flashcards covering states of matter, phase changes, phase diagrams, kinetic molecular theory, and related concepts from the PhET exploration notes.

Plasma

A high-energy state of matter consisting of ionized particles; most common in the universe (e.g., stars) but not typically the focus for Earth-school chemistry.

Solid

A state of matter with definite shape and volume; particles vibrate in fixed positions and are tightly packed.

Liquid

A state of matter with definite volume but no fixed shape; particles flow past one another and are less tightly arranged than in a solid.

Gas

A state of matter with neither fixed shape nor fixed volume; particles are far apart, move rapidly, and fill available space.

Neon (solid Neon)

A solid sample used in the States of Matter activity to observe particle spacing and motion when cooled.

Phase

A distinct form of matter with uniform properties; solids, liquids, and gases are different phases.

Phase diagram

A chart showing which phase is stable at different temperatures and pressures; shows boundaries between solid, liquid, and gas.

Phase change

Transition between phases (melting, freezing, vaporization, condensation, sublimation, deposition) that involves energy transfer.

Melting

Solid to liquid; occurs when a solid absorbs heat and its particles gain enough energy to break fixed positions.

Freezing

Liquid to solid; occurs when a liquid loses energy and its particles arrange into a rigid structure.

Vaporization

Liquid to gas; includes evaporation (surface) and boiling (throughout) as energy is absorbed.

Condensation

Gas to liquid; gas loses energy and particles crowd together into a liquid.

Sublimation

Solid to gas; energy absorbed enough to skip the liquid phase.

Deposition

Gas to solid; energy released as gas particles arrange into a solid.

Melting (X(s) → X(l))

Phase change from solid to liquid for substance X.

Freezing (X(l) → X(s))

Phase change from liquid to solid for substance X.

Vaporization (X(l) → X(g))

Phase change from liquid to gas for substance X.

Condensation (X(g) → X(l))

Phase change from gas to liquid for substance X.

Sublimation (X(s) → X(g))

Phase change from solid to gas for substance X.

Deposition (X(g) → X(s))

Phase change from gas to solid for substance X.

State symbols

s, l, g, aq indicate the physical state of a substance in chemical equations.

Critical point

The end point of the liquid–gas boundary on a phase diagram; beyond it, liquid and gas are indistinguishable.

Latent heat

Energy absorbed or released during a phase change at a constant temperature; temperature does not change during the phase transition.

Temperature

A measure of the average kinetic energy of particles; units include Kelvin (K) and Celsius (°C).

Kelvin (K)

Absolute temperature scale used in science; 0 K is absolute zero.

Celsius (°C)

Temperature scale where 0°C is the freezing point of water; Celsius is offset from Kelvin by 273.15.

K = °C + 273

Conversion formula between Celsius and Kelvin.

Absolute zero

The theoretical lowest possible temperature where particle motion ceases (0 K); not reachable in practice.

Kinetic Molecular Theory (KMT)

Theory explaining gas behavior: particles are in constant, random motion and undergo elastic collisions; energy depends on temperature.

Kinetic energy

Energy of motion; increases with temperature; higher kinetic energy means faster particles.

Elastic collisions

Collisions in which kinetic energy is conserved; gas particles do not lose energy in the collision.

Gas particle motion

Gas particles are in constant, random motion.

Pressure

Force per unit area exerted by gas on container walls; increases with temperature and particle collisions.

Wall collisions

Encounters of gas particles with the container walls; can be counted in simulations to quantify activity.

Collision counter

A feature in simulations that counts wall collisions over time.

Relationship: temperature and pressure

Increasing temperature generally increases pressure (more energetic collisions); decreasing temperature lowers pressure.

Relationship: temperature and kinetic energy

Higher temperature corresponds to higher average kinetic energy of particles.