To draw the Lewis structure of ClCN, we first need to determine the number of valence electrons available in the molecule.
a) Number of valence electrons:
Chlorine (Cl) has 7 valence electrons, carbon (C) has 4, and nitrogen (N) has 5. Adding these together gives us:
- Cl: 7
- C: 4
- N: 5
- Total: 7 + 4 + 5 = 16 valence electrons
b) Number of lone pairs on N:
In the Lewis structure of ClCN, nitrogen is typically drawn with one lone pair. Therefore, nitrogen has 1 lone pair.
c) Formal charge on all the atoms:
To calculate the formal charge, we use the formula: Formal Charge = (Valence electrons) – (Non-bonding electrons) – 0.5(Bonding electrons).
- Cl: 7 – 6 – 0.5(2) = 0
- C: 4 – 0 – 0.5(4) = 0
- N: 5 – 2 – 0.5(2) = 1
The formal charges are as follows: Cl = 0, C = 0, N = 1.
d) Number of sigma and pi bonds:
In ClCN, there is one triple bond between carbon and nitrogen, which consists of:
- 1 sigma bond (single bond) and 2 pi bonds (from the triple bond).
Additionally, there is one single bond between carbon and chlorine, which contributes:
- 1 sigma bond.
So, overall the molecule has 2 sigma bonds (one from Cl-C and one from C=N) and 2 pi bonds.
e) Hybridization of C in the molecule:
Carbon is involved in a triple bond with nitrogen and a single bond with chlorine. Therefore, the hybridization of carbon is sp.