States of Matter & Gas Laws — 60 Terms Defined

Root Mean Square Speed States of Matter & Gas Laws m/s The square root of the average of the squared molecular speeds in a gas sample. c_rms = √(3RT / M)

Schottky Defect States of Matter & Gas Laws Dimensionless A point defect in which equal numbers of cations and anions are missing from their lattice sites.

Simple Cubic States of Matter & Gas Laws Dimensionless A crystal arrangement with particles only at the eight corners of a cubic unit cell. 1 atom per cell, 52% packing

Solid State States of Matter & Gas Laws Dimensionless The state of matter in which particles are held in fixed positions, giving a definite shape and volume.

Sublimation States of Matter & Gas Laws kJ/mol The direct conversion of a solid into a vapour without passing through the liquid state. ΔH_sub = ΔH_fus + ΔH_vap

Supercritical Fluid States of Matter & Gas Laws K, Pa A substance held above both its critical temperature and critical pressure, where liquid and gas phases are indistinguishable. T > T_c and p > p_c

Surface Tension States of Matter & Gas Laws N/m The energy required to increase the surface area of a liquid by unit amount, arising from unbalanced intermolecular forces at the surface. γ = F / L

Triple Point States of Matter & Gas Laws K, Pa The unique temperature and pressure at which the solid, liquid and vapour phases of a substance coexist in equilibrium.

Unit Cell States of Matter & Gas Laws pm The smallest repeating three-dimensional unit that, when stacked, reproduces the entire crystal lattice. ρ = ZM / (a³N_A)

Van der Waals Equation States of Matter & Gas Laws Various A modified equation of state that corrects the ideal gas law for molecular volume and intermolecular attraction. (p + an²/V²)(V − nb) = nRT

Vapour Pressure States of Matter & Gas Laws Pa The pressure exerted by a vapour in dynamic equilibrium with its liquid or solid at a given temperature. ln p = −ΔH_vap / RT + C

Viscosity States of Matter & Gas Laws Pa·s A liquid's resistance to flow, arising from internal friction between adjacent layers of molecules. F = ηA (dv/dx)