The structure of liquid or amorphous metals is described by means of an harmonic approxima tion where atoms vibrate around the equilibrium positions of a random hard sphere network. This model depends on three parameters, of which the only adjustable one is the atomic vibration frequency, which is shown to be proportional to the Debye frequency of the corresponding crystalline phase. The atomic diameter is deduced from the position of the structure factor first peak and turns out to be equal to the Goldschmidt diameter. The packing fraction temperature variations are at tributed to presence of a variable number of randomly distributed atomic holes and deduced from density measurements. Good agreement with experimental structure factor determinations is found for a wide variety of liquid metals.