States of matter

Ideal gases and lattices

An ideal gas has particles of negligible volume, no intermolecular forces and perfectly elastic collisions. It obeys $pV=nRT$ with $p$ in Pa, $V$ in m³, $T$ in K and $R=8.31\ \text{J K}^{-1}\text{mol}^{-1}$. Real gases deviate at high pressure (particle volume matters) and low temperature (intermolecular forces matter); they behave most ideally at high temperature and low pressure. Solids can be giant ionic, giant molecular (covalent), simple molecular or metallic lattices.