= H2CO3

carbonic acid

formula | H_2CO_3 Hill formula | CH_2O_3 name | carbonic acid mass fractions | C (carbon) 19.4% | H (hydrogen) 3.25% | O (oxygen) 77.4%

Draw the Lewis structure of carbonic acid. 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), hydrogen (n_H, val = 1), and oxygen (n_O, val = 6) atoms: n_C, val + 2 n_H, val + 3 n_O, val = 24 Calculate the number of electrons needed to completely fill the valence shells for carbon (n_C, full = 8), hydrogen (n_H, full = 2), and oxygen (n_O, full = 8): n_C, full + 2 n_H, full + 3 n_O, full = 36 Subtracting these two numbers shows that 36 - 24 = 12 bonding electrons are needed. Each bond has two electrons, so in addition to the 5 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: Fill in the 1 bond by pairing electrons between adjacent highlighted atoms: Answer: | |

3D structure

molar mass | 62.024 g/mol

PubChem CID number | 767 SMILES identifier | C(=O)(O)O InChI identifier | InChI=1S/CH2O3/c2-1(3)4/h(H2, 2, 3, 4)