What is the geometry of the carbonate dianion, #CO_3^(2-)#?

1 Answer
May 2, 2017

Answer:

Carbonate anion is trigonal planar to a first approximation.........

Explanation:

We have #4+3xx6+2=24*"electrons"# to distribute around 3 oxygen and 1 carbon atoms.......

A Lewis structure gives #O=C(-O^(-))_2#, which gives one neutral (#sp^2-"hybridized"#) oxygen, and 2 formally anionic oxygen centres (#sp^3-"hybridized"#)......The central carbon is #sp^2-"hybridized"#.

If we ignore the #pi-"bond"#, there are THREE regions of electron density around the central carbon, and trigonal planar geometry is adopted, with #/_O-C-O=120^@#.