Since for atomic and molecular gases, the classical ideal gas law is well suited in most cases, let us describe the equation of state for elementary particles with mass formula_24 and spin formula_25 that takes into account of quantum effects. In the following, the upper sign will always correspond to Fermi-Dirac statistics and the lower sign to Bose–Einstein statistics. The equation of state of such gases with formula_26 particles occupying a volume formula_27 with temperature formula_28 and pressure formula_29 is given by