Question

If the symbol X represents a central atom, Y outer atoms, and Z lone pairs on the central atom, the structure `Y- :X: -Y` could be abbreviated as `XY_2Z_2`. How would you classify these structures by the hybridization of the central atom?

Answer 1

The hybridization about the central atom `X` would be `sp^3` hybridization.

Explanation:

Two lone pair on the central and two species bonded to the central atom in the species would constitute tetrahedral electronic structure and bent molecular geometry , with bond angles less than `109.5` degrees.

There are 4 electron clouds around the central atom, so the hybridization is `sp^3`.

A similar species `Y-X-Y` with no lone pair about the species would have `sp` hybridization.

Let `s` = the number of `sigma` bond about the species.
Count the `sigma` bonds about the species (including dative bonds) and subtract one to attain the `sp^s` hybridization.

In other words: `sp^(s-1)` for `s` `sigma` bonds. Factor in any lone pair about the central atom.

Keep in mind for a species with a greater number of electron (larger atoms), we will have to start to consider the `d` orbitals, especially those species which can become hypervalent which occur after the `n=2` shell.