Matter in Our Surroundings – Physical Nature & States

Vocabulary flashcards summarising key terms and definitions from the chapter "Matter in Our Surroundings," focusing on particle nature, states of matter, phase changes, and related physical concepts.

Matter

Anything that occupies space, has mass, and is made up of particles.

Particle Nature of Matter

Concept that matter is composed of tiny, discrete particles rather than being continuous.

Diffusion

Spontaneous intermixing of particles of two substances due to their kinetic energy.

Kinetic Energy (of particles)

Energy possessed by particles due to their motion; increases with temperature.

Inter-particle Spaces

Gaps between particles of matter; largest in gases, least in solids.

Force of Attraction

Intermolecular force holding particles together; strongest in solids, weakest in gases.

Solid

State of matter with definite shape and volume, high rigidity, and negligible compressibility.

Liquid

State of matter with definite volume but no fixed shape; flows and is less rigid than solids.

Gas

State of matter with neither definite shape nor volume; highly compressible and diffuses rapidly.

Density

Mass per unit volume of a substance (ρ = m/V).

Rigidity

Tendency of a solid to resist shape change when force is applied.

Compressibility

Property that describes how much the volume of matter decreases under pressure; highest in gases.

Melting Point

Temperature at which a solid converts to liquid at atmospheric pressure (e.g., ice at 273 K).

Fusion

Process of a solid changing into a liquid upon heating; synonym for melting.

Latent Heat of Fusion

Heat required to change 1 kg of a solid into liquid at its melting point without temperature change.

Boiling Point

Temperature at which a liquid changes to gas throughout its bulk at atmospheric pressure (water: 373 K).

Latent Heat of Vaporisation

Heat required to convert 1 kg of a liquid into vapour at its boiling point without temperature change.

Sublimation

Direct change of a solid to gas without passing through the liquid state (e.g., camphor, dry ice).

Deposition

Direct change of a gas to solid without becoming liquid.

Dry Ice

Solid carbon dioxide that sublimates at atmospheric pressure; used as a refrigerant.

Evaporation

Surface phenomenon where particles escape from a liquid into vapour below boiling point.

Factors Affecting Evaporation

Surface area ↑, temperature ↑, humidity ↓, wind speed ↑ all increase the rate of evaporation.

Cooling by Evaporation

Process where liquid absorbs heat from surroundings during evaporation, causing temperature drop.

Humidity

Amount of water vapour present in air; high humidity lowers evaporation rate.

CNG (Compressed Natural Gas)

Natural gas stored under high pressure for use as fuel; demonstrates gas compressibility.

LPG (Liquefied Petroleum Gas)

Petroleum gas liquefied under pressure, used as domestic fuel.

Bulk Phenomenon

Process (e.g., boiling) involving particles from the entire volume of a liquid changing state.

Surface Phenomenon

Process (e.g., evaporation) involving particles only at the surface undergoing state change.

Kelvin Scale

SI temperature scale where 0 °C equals 273 K; used for scientific temperature measurement.

Diffusion Rate (state comparison)

Fastest in gases, slower in liquids, extremely slow in solids due to differing particle mobility.

Liquefaction of Gases

Conversion of a gas to liquid by increasing pressure and/or decreasing temperature.

Pressure (gas)

Force per unit area exerted by gas particles colliding with container walls; measured in pascals.

S.I. Unit of Volume

Cubic metre (m³); common laboratory unit is litre (L).

S.I. Unit of Mass

Kilogram (kg).