If \(P(x,\,y,\,z)\ \rm{d}x\ \rm{d}y\ \rm{d}z\) is the probability of finding an electron in the volume element \(\rm{d}x\ \rm{d}y\ \rm{d}z\) at the point of a molecular entity with coordinates \(x,\,y,\,z\), then \(P(x,\,y,\,z)\) is the electron density at this point. For many purposes (e.g. X-ray scattering, forces on atoms) the system behaves exactly as if the electrons were spread out into a continuously distributed charge. The term has frequently been wrongly applied to negative charge population.