Lewis structure of CO
10 valence electrons. One C≡O triple bond, with one lone pair on C.
Lewis structure
10 valence electronsi
A triple bond with a lone pair on each atom: the formal charges are -1 on C and +1 on O.
Formal charges: C −1, O +1
Why this shape
- C has 4 valence electrons. In the Lewis structure it makes one triple bond to O and keeps one lone pair, which leaves it a formal charge of −1.
- Steric number = one sigma bond + one lone pair = 2, so C is sp hybridised. A double or triple bond counts once: only its sigma bond uses a hybrid orbital.
- Two electron pairs point in opposite directions, along a line (linear electron geometry). With only two atoms, the molecule itself is a straight line.
- Two atoms always lie on a straight line, so there is no bond angle.
- The two atoms are different, so the bond is polar and so is CO.
Molecular orbitals
14 electrons3bond order
diamagnetic
diamagnetic
(Nb − Na) / 2 = (10 − 4) / 2
σ1s² σ*1s² σ2s² σ*2s² (π2px² = π2py²) σ2pz²
How to draw it
- Count the valence electrons: C 4 + O 6 = 10 valence electrons, 5 pairs.
- Put C in the middle and join it to the other atom with single bonds.
- Give each outer atom lone pairs until it has an octet (H needs only two electrons), then put any electrons left over on the central atom.
- Where an atom is still short of an octet, turn a lone pair of its neighbour into a shared pair: that makes a double or triple bond.
- Result: one C≡O triple bond, with one lone pair on C.
- Formal charge = valence electrons − lone pair electrons − number of bonds. Here: C −1, O +1.
Class 11, Chapter 4 Chemical Bonding and Molecular Structure.
Lewis structure of CO: quick answers
How many valence electrons are in CO?
C 4 + O 6 = 10 valence electrons, 5 pairs.
What are the formal charges in the Lewis structure of CO?
C −1, O +1; every other atom is zero. Formal charge = valence electrons - lone pair electrons - number of bonds.
How many lone pairs are in the Lewis structure of CO?
2 in all, 1 of them on the central C.