What are the resonance structures for #CO_3^-2#?

1 Answer
Jan 27, 2017


This is a carbonate ion. A resonance structure means that there are more than one way to draw the ion.


First, determine the total number of electrons available:

1 Carbon - 4
3 Oxygen - #6(3) = 18#

And the charge of #-2# gives you an additional 2 electrons.

Hence, there are 24 electrons in total (#4+18+2=24#)

Carbon would be in the middle which gives you


However, note that carbon does not have a full octet shell. Hence, a pair of electrons from oxygen needs to come over and form a double bond. Note that the double bond can come from any oxygen atom which gives carbonate its resonance structure.