What is the formal charge of C2H2
To calculate the formal charge of a molecule, you need to subtract the number of valence electrons in each atom from the number of electrons that the atom is actually contributing to the molecule.
For C2H2 (ethyne or acetylene), the Lewis structure is:
H - C≡C - H
Both carbon atoms in C2H2 are contributing 2 valence electrons each, while each hydrogen atom is contributing 1 valence electron.
The formal charge of each carbon atom can be calculated as follows:
For carbon in the middle of the molecule:
FC = Valence electrons - (Bonds + Lone pairs)
FC = 4 - (3 + 0)
FC = 1
For the carbon at the end of the molecule:
FC = Valence electrons - (Bonds + Lone pairs)
FC = 4 - (2 + 0)
FC = 2
Therefore, the formal charge of each carbon atom in C2H2 is as follows:
- Carbon in the middle of the molecule: +1
- Carbon at the end of the molecule: +2