Solids, Liquids, and Gases: States of Matter and Thermal Properties

Vocabulary flashcards covering the states of matter, density, molar properties, thermal expansion, and ideal-gas processes based on Chapter 18 lecture notes.

Solid

A rigid macroscopic system consisting of particle-like atoms connected by spring-like molecular bonds, where each atom vibrates around a fixed equilibrium position.

Liquid

A nearly incompressible state of matter that flows and deforms to fit the shape of its container, indicating molecules are close together but free to move.

Gas

A highly compressible fluid system in which molecules move through space as free, noninteracting particles except during occasional collisions with walls or other molecules.

Mass Density

The ratio of an object’s or material’s mass to its volume ($\rho = M/V$), with SI units of $kg/m^3$.

Number Density

The quantity of atoms or molecules per cubic meter in a system, expressed as $\frac{N}{V}$ with SI units of $m^{-3}$.

Atomic Mass Number ($A$)

The sum of the number of protons and neutrons in the nucleus of an atom.

Atomic Mass Unit ($u$)

A unit of mass defined as $1.66 \times 10^{-27} \, kg$.

Mole

The amount of substance containing Avogadro’s number ($N_A = 6.02 \times 10^{23} \, mol^{-1}$) of particles.

Molar Mass ($M_{mol}$)

The mass of $1 \, mol$ of a substance, typically measured in $kg/mol$.

Kelvin Temperature Scale

A temperature scale with the same unit size as Celsius but with the zero point at absolute zero, calculated as $T_K = T_C + 273$.

Absolute Zero

The temperature at which all gases extrapolate to zero pressure, equal to $-273^{\circ}C$ or $0 \, K$.

Coefficient of Linear Expansion ($\alpha$)

The proportionality coefficient for solids that relates the fractional change in length ($\Delta L / L$) to the change in temperature ($\Delta T$).

Coefficient of Volume Expansion ($\beta$)

The proportionality coefficient that relates the fractional change in volume ($\Delta V / V$) to the change in temperature ($\Delta T$); for solids, $\beta = 3\alpha$.

Phase Diagram

A graph used to show how the phases and phase changes of a substance vary with both temperature and pressure.

Ideal-Gas Model

A model in which gas atoms are treated as hard spheres that travel through space and interact only through perfectly elastic collisions.

Universal Gas Constant ($R$)

A constant used in the ideal-gas law equal to $$8.31 \, J/mol \, K$.

Boltzmann’s Constant ($k_B$)

A constant used in the ideal-gas law equal to $1.38 \times 10^{-23} \, J/K$.

pV Diagram

A graph of pressure versus volume used to represent ideal-gas processes.

Quasi-static Process

A process that occurs slowly enough (like slowly pulling or pushing a piston) that it can be reversed and represented as a trajectory on a $pV$ diagram.

Isochoric Process

An ideal-gas process that occurs at a constant volume.

Isobaric Process

An ideal-gas process that occurs at a constant pressure.

Isothermal Process

An ideal-gas process that occurs at a constant temperature, represented on a $pV$ diagram as a hyperbola.