How do you determine steric numbers?

1 Answer
anor277
Jul 14, 2018

This is an old term....

Explanation:

The steric number of a given molecule is the number of atoms BOUND to the central atom of a molecule PLUS the number of lone pairs associated with the central atom.

For instance for #SF_4# there are FOUR #S-F# #sigma-"bonds"#, PLUS ONE lone pair associated with the central sulfur atom. And so for #SF_4#, whose geometry is based on a trigonal bipyramid, the steric number is #5#... And the steric number directly gives ELECTRONIC geometry...#2="linear"#, #3="trigonal planar"#, #4="tetrahedral"#, #5="trigonal bipyramdal"#, #6=??#..

The steric number determines #"ELECTRONIC NOT MOLECULAR GEOMETRY...."#

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