Question #73746

2 Answers
Oscar L.
Jun 15, 2016

Actually it doesn't. In the planar molecule the #2s# orbital on oxygen mixed with only the two #2p# orbitals in the same plane to make the bonds.

Explanation:

A diagram of the molecular orbitals is given here. Note that the #2p_z# remains unchanged.

https://en.wikipedia.org/wiki/Molecular_orbital_diagram

Simon Moore
Jun 15, 2016

It is a consequence of both Hund's rule of maximum multiplicity (which gives oxygen two unpaired electrons) and achievement of maximum separation of the orbitals.

Explanation:

Following Hunds rule electronic configuration of oxygen is #1s^2 2s^2 2px^2 2py^1 2pz^1#.

Oxygen, therefore, has two unpaired electrons which can bond with the two hydrogen atoms. In order to obtain maximum separation of the electron orbitals from the 3 atoms, bonding is achieved by the formation of four #sp^3# hybrid orbitals. However, two of these contain only non-bonded pairs, so the overall shape looks more like a "bent" V than a normal tetrahedron. Repulsion from the remaining lone pair on the oxygen atom means the bond angle is reduced to around 105 degrees..

Related questions
See all questions in Orbital Hybridization
Impact of this question
2180 views around the world
You can reuse this answer
Creative Commons License