An equivalent approach is to think of the electron's charge. Because the electron's exact position is not defined, we can think of its charge as being nonuniformly distributed in the atom or molecule. So, each point in space will have a partial charge. Electron Density Isosurfaces. Electron density isosurfaces are similar to isobars on a weather map.
Isobars are lines connecting points with the equal air pressure.
Iso- means equal. Electron density isosurfaces are surfaces with equal electron densities around an atom or molecule. They can be displayed as solid surfaces, transparent surfaces, or mesh surfaces. They are gray unless some other data is superimposed on them. There are two default density values used for these surfaces.