Numford
Hybridisation

Hybridisation of O₂

Each O atom is sp² hybridised (hybridization by the VSEPR count): 1 sigma bond and 2 lone pairs give a linear shape.

OO
  • O

O₂Oxygen

Linear

Each O: 1 sigma bond, 2 lone pairs

i

Two atoms always lie on a line. Hybridisation of an atom in a two atom molecule is a count of its sigma bonds and lone pairs; many books do not ask it.

  • Hybridisationsp²
  • Polaritynon-polar
  • Bond order2

Why this shape

  1. Each O has 6 valence electrons. It uses two in one double bond to O, so four are left as two lone pairs.
  2. 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.
  3. 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.
  4. Two atoms always lie on a straight line, so there is no bond angle.
  5. Both atoms are the same, so the bond is non-polar.

Lewis structure

12 valence electrons
i

The Lewis structure pairs every electron, but O2 is paramagnetic with two unpaired electrons. Only molecular orbital theory explains that.

OO

Formal charges: none

Molecular orbitals

16 electrons
2bond order
paramagnetic

(Nb − Na) / 2 = (10 − 6) / 2

1s1s2s2s2p2pσ1sσ*1sσ2sσ*2sσ2pzπ2pπ*2pσ*2pzO atomMoleculeO atomEnergy

σ1s² σ*1s² σ2s² σ*2s² σ2pz² (π2px² = π2py²) (π*2px¹ = π*2py¹)

Working

Why this hybridisation and shape

  1. Each O has 6 valence electrons. It uses two in one double bond to O, so four are left as two lone pairs.
  2. 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.
  3. 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.
  4. Two atoms always lie on a straight line, so there is no bond angle.
  5. Both atoms are the same, so the bond is non-polar.

Class 11, Chapter 4 Chemical Bonding and Molecular Structure.

Questions

Hybridisation of O2: quick answers

What is the hybridisation of O2?

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.

What is the shape of O2 and its bond angle?

Linear. 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.

Is O2 polar or non-polar?

Non-polar. Both atoms are the same, so the bond is non-polar.

Try any molecule