# Which atom goes in the middle of a lewis dot structure?

I've read online in multiple sites that the least electronegative atom goes in the middle with the exception of H, which always goes on the outside.

However, in the molecule NaCN, C is in the middle. Could anyone explain to me what is going on with this molecule?

• It's not really valid to have a Lewis structure for an ionic compound. Leave the Na out. – Brinn Belyea Sep 23 '14 at 2:04
• @brinnb So is that why the rule does not generalize to this specific molecule? – Vedaad Shakib Sep 23 '14 at 2:08

Your molecule is sodium cyanide, an ionic compound. The cyanide group, CN-, carries a negative charge. If we consider where that charge lies in the ion, it is a bit confusing. The basic structure of the cyanide is ${\ce :C:::N:^-}$ .