Lewis structure of O₂
12 valence electrons. One O=O double bond, with two lone pairs on O.
Lewis structure
12 valence electronsi
The Lewis structure pairs every electron, but O2 is paramagnetic with two unpaired electrons. Only molecular orbital theory explains that.
Formal charges: none
Why this shape
- Each O has 6 valence electrons. It uses two in one double bond to O, so four are left as two lone pairs.
- Steric number = one sigma bond + two lone pairs = 3, so each O is sp² hybridised. A double or triple bond counts once: only its sigma bond uses a hybrid orbital.
- Three electron pairs point to the corners of a flat triangle (trigonal planar 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.
- Both atoms are the same, so the bond is non-polar.
Molecular orbitals
16 electrons2bond order
paramagnetic
paramagnetic
(Nb − Na) / 2 = (10 − 6) / 2
σ1s² σ*1s² σ2s² σ*2s² σ2pz² (π2px² = π2py²) (π*2px¹ = π*2py¹)
How to draw it
- Count the valence electrons: 2 × O 6 = 12 valence electrons, 6 pairs.
- Join the atoms with single bonds: the O atoms to each other and the H atoms around them.
- 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 O=O double bond, with two lone pairs on O.
- Formal charge = valence electrons − lone pair electrons − number of bonds. Here: none.
Class 11, Chapter 4 Chemical Bonding and Molecular Structure.
Lewis structure of O2: quick answers
How many valence electrons are in O2?
2 × O 6 = 12 valence electrons, 6 pairs.
What are the formal charges in the Lewis structure of O2?
Every atom has a formal charge of zero.
How many lone pairs are in the Lewis structure of O2?
4 in all, 2 of them on the central O.