And #"VSEPR"-="Valence shell electron pair repulsion theory."#
And I will give ONE bond, the VESPER treatment of nitrate ion...we gots #NO_3^(-)#...and there are ……
#3xx6_"oxygen valence electrons"+5_"nitrogen valence electrons"+1_"negative charge"# #="24 electrons"#, i.e. TWELVE electron pairs to distribute over FOUR CENTRES....
And we get....#O=stackrel(+)N(-O^(-))_2#...THREE of the four participating atoms have a formal charge...the leftmost oxygen is NEUTRAL (it has 8 electrons), the nitrogen has SIX electrons, and therefore has a FORMAL POSITIVE charge...and two of the oxygens bear 9 electrons, and thus have a FORMAL NEGATIVE charge... The overall charge is this #+1-1-1=-1#.
Can you try for #SO_4^(2-)#?
