The mercury (Hg) has 80 electrons. The electrons are distributed in the s, p, d and f orbitals. The electronic configuration of Hg can be shown as-. We can see that there are two filled d-orbitals 3d and 4d. There is only one filled f orbital which is 4f. The electron cloud of the s, p, d and f are different due to their different screening and penetration effect towards the nucleus. The electron cloud of f-orbital is most diffuse than the other three. The outermost electrons of mercury is , which is its valence electrons i.e. (+2).