Lewis Dot Structures? Two of them.?

Question

SF6 and NO2^-1 please and thank you. Im stuck on these two.

Answer 1

SF6:
The center atom S originally has 6 electrons in its valence shell. Since S is in period 3 in the periodic table, its has "d" orbital. Through sp3d2 hybridization, it can bond to 6 fluorine atoms, thus resulting a total 12 electrons in the valence shell. Please read the reference:
http://en.wikipedia.org/wiki/SF6

NO2(-):
It has two resonance structures (here I only show the bonding electrons, you fill the non-bonding electrons, please):
O::N>O <==> O where either N>O or O http://en.wikipedia.org/wiki/Resonance_structures