Question

How do I determine the hybridization and bonding in ammonia?

Answer 1

Here's how to do it.

Explanation:

You draw the Lewis structure (Step 1) and use VSEPR theory to determine its electron domain geometry as tetrahedral and its molecular shape (Step 2) as a trigonal pyramid.

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Then you consult a table like the one below.

Hybridization
(Adapted from SlideShare)

You find that the `"N"` atom uses `"sp"^3` orbitals, so you draw four tear-drop shapes pointing towards the corners of a tetrahedron (Step 3).

The `"H"` atoms use their `"1s"` orbitals for bonding, so you draw small circles intersecting with three of the `"sp"`3 orbitals.

That shows that the `"N-H"` bonds are σ bonds formed by the overlap of `"sp"^3` orbitals of `"N"` and `"1s"` orbitals of `"H"`.

However, the molecular orbitals include both the `"N"` and `"H"` nuclei.

NH3

In the diagram above, the bond-line drawing shows that the `"H"` nuclei are completely inside the larger teardrop-shaped `"sp"^3"-s"` σ molecular orbitals.