Po (Z = 84)
e- config (full)
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p4
# inner electrons?
I was told valence e-'s for main group elements were s and p orbitals, so valence e- = 6s2 6p4, which is 6 and 84-6=78 inner e-. But it was wrong. Help?