What the shape of an ammonia molecule?
The ammonia molecule is a trigonal pyramid to a first approx., with
How did we predict this shape? We know the ammonia molecule has 8 electrons to distribute nitrogen: one pair of electrons comprise the nitrogen-centred lone pair, and the other 6 electrons constitute the
There are thus 4 electrons pair to distribute around nitrogen. And their arrangement in a tetrahedron is the first approximation of the molecular structure. But we describe molecular shape on the basis of atomic geometry, not electronic geometry. While the 4 electron pairs are distributed as a tetrahedron about
When ammonia reacts as a base upon reaction with water to give ammonium ion,