The steric number is the number of atoms bonded to a central atom of a molecule plus the number of lone pairs attached to the central atom. The steric number of a molecule is used in VSEPR (valence shell electron pair repulsion) theory to determine the molecular geometry of a molecule.

What does steric number tell you?

Steric number: The number of atoms, groups, or lone pairs (i.e., electron clouds) around a central atom. The steric number determines molecular geometry.

What is steric number and how is it calculated?

One way to determine the hybridization of an atom is to calculate its steric number, which is equal to the number of sigma bonds surrounding the atom plus the number of lone pairs on the atoms. In this video, we focus on atoms with a steric number of 4, which corresponds to sp³ hybridization.