What is the geometry and hybridization of "H"_2"S"? How many sigma and pi bonds does it have?

1 Answer
Feb 17, 2016

Sigma bonds will always be involving orbitals that are symmetric about the internuclear axis, whether it be 3s with 3p_z, 4p_z with 3d_(z^2), or other similar combinations.

"H"_2"S", being an analog of "H"_2"O", has the same molecular geometry: bent, a derivative of the tetrahedral electron geometry. One might call "tetrahedral", AX_4 geometry.

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When sulfur could potentially bond with four atoms, it hybridizes its 3s and 3p orbitals to generate four sp^3 hybrid orbitals, two of which are used to overlap head-on with hydrogen's 1s atomic orbitals.

In other words, sulfur utilizes two identical, compatible sp^3 hybrid orbitals, overlapping each one with a hydrogen 1s orbital.

The two others are used to hold one lone pair of electrons each. See how water looks similar?

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So, let me ask you this:

  • Along which bond is each internuclear axis? (There are two.)
  • Are the 1s and sp^3 orbital combinations along the internuclear axis?
  • If you grab each hydrogen and rotate it about their respective internuclear axes, will you ever see a different "H"_2"S" molecule?
  • If not, then it is a sigma bond. (The answer is no, so it is a sigma bond.)

If you followed all that, you should conclude that there are two sigma bonds: the "H"-"S" and "S"-"H".

Have you completely accounted for both bonds? (Yes. Hydrogen has no other valence electrons to contribute, and hydrogen normally prefers not to make more than one bond.)

Therefore, there are no pi bonds on "H"_2"S".