Input interpretation
carbonate anion | structure diagram
Result
Draw the Lewis structure of carbonate anion. Start by drawing the overall structure of the molecule, ignoring potential double and triple bonds: Count the total valence electrons of the carbon (n_C, val = 4) and oxygen (n_O, val = 6) atoms, including the net charge: n_C, val + 3 n_O, val - n_charge = 24 Calculate the number of electrons needed to completely fill the valence shells for carbon (n_C, full = 8) and oxygen (n_O, full = 8): n_C, full + 3 n_O, full = 32 Subtracting these two numbers shows that 32 - 24 = 8 bonding electrons are needed. Each bond has two electrons, so in addition to the 3 bonds already present in the diagram add 1 bond. To minimize formal charge oxygen wants 2 bonds and carbon wants 4 bonds. Identify the atoms that want additional bonds and the number of electrons remaining on each atom. The net charge has been given to the most electronegative atom, oxygen, in 2 places: Fill in the 1 bond by pairing electrons between adjacent highlighted atoms, noting the formal charges of the atoms. Double bonding carbon to the other highlighted oxygen atoms would result in an equivalent molecule: Answer: | |