A gas which obeys the general gas law perfectly (PV = NRT). The term implies\\
(1) atomic-sized gas particles,\\
(2) the molecules are in random motion and obey Newton's laws of motion,\\
(3) the total number of molecules is large,\\
(4) the volume of the [[molecule|molecules]] is a negligibly small fraction of the volume occupied by the gas,\\
(5) no appreciable forces act on the molecules except during a collision, and\\
(6) collisions are elastic and are of negligible duration.