Matter in Our Surroundings – Vocabulary Flashcards

These 35 vocabulary flashcards cover the essential terms and definitions from the lecture notes on “Matter in Our Surroundings,” helping you review states of matter, particle behavior, state changes, and evaporation concepts.

Matter

Anything that occupies space and has mass.

Particle Theory of Matter

The idea that all matter is made of tiny, continuously moving particles with spaces and forces of attraction between them.

Diffusion

The natural intermixing of particles from two substances due to their random motion.

Kinetic Energy (of particles)

Energy possessed by moving particles; increases with temperature.

Force of Attraction

Intermolecular pull that keeps particles together; strongest in solids, weakest in gases.

Solid

State of matter with definite shape and volume, high density, negligible compressibility, and strong intermolecular forces.

Liquid

State of matter with definite volume but no fixed shape; flows, is less dense than solids, and has moderate intermolecular forces.

Gas

State of matter with neither fixed shape nor volume, lowest density, high compressibility, and negligible intermolecular forces.

Density

Mass per unit volume of a substance (density = mass ÷ volume).

Rigidity

Tendency of a solid to maintain shape when force is applied.

Compressibility

Ability of a substance, mainly gases, to decrease volume under pressure.

Fluidity

Capacity of a substance (liquids and gases) to flow.

Melting

Process of changing a solid into a liquid by heating.

Melting Point

Fixed temperature at which a solid becomes a liquid (0 °C for ice).

Freezing

Process of changing a liquid into a solid by cooling.

Freezing Point

Temperature at which a liquid turns into a solid (0 °C for water).

Boiling

Rapid vaporisation of a liquid occurring throughout the bulk at a fixed temperature.

Boiling Point

Temperature at which a liquid’s vapor pressure equals atmospheric pressure (100 °C for water).

Evaporation

Slow conversion of a liquid’s surface molecules into vapor below its boiling point.

Condensation

Change of a gas into a liquid on cooling.

Sublimation

Direct change of a solid to gas (and vice-versa) without passing through liquid state.

Interconversion of States

Reversible change of matter from one physical state to another by altering temperature or pressure.

Latent Heat

Hidden heat absorbed or released during a change of state without temperature change.

Latent Heat of Fusion

Heat required to convert 1 kg of solid to liquid at its melting point without temperature rise.

Latent Heat of Vaporisation

Heat required to convert 1 kg of liquid to gas at its boiling point without temperature rise.

Kelvin Scale

SI temperature scale starting at absolute zero; conversion: K = °C + 273.

Celsius Scale

Temperature scale based on 0 °C for freezing and 100 °C for boiling of water.

Effect of Temperature

Increasing temperature raises particle kinetic energy, weakening attractions and causing state changes.

Effect of Pressure

Applying pressure brings gas particles closer, increasing attractions and leading to liquefaction.

Evaporative Cooling

Cooling produced when high-energy surface molecules evaporate, absorbing heat from surroundings.

Volatile Substance

Liquid with high vapor pressure that evaporates quickly (e.g., acetone, perfume).

Humidity

Amount of water vapor in air; higher humidity slows evaporation.

Surface Area (in evaporation)

Larger exposed area accelerates evaporation by allowing more molecules to escape.

Wind Speed

Air movement that removes saturated air, enhancing evaporation rate.

Compressed Natural Gas (CNG)

Natural gas stored at high pressure in cylinders for fuel due to gas compressibility.