How many lone pairs are there in H2O?

2

It is important to know that the O in H2O has 2 bond pairs and 2 lone pairs (4 total pairs).  Not too many people know that the electron pair orientation around O is tetrahedral.  Keep in mind that two corners of the tetrahedron are “missing” because they are occupied by lone pairs, not atoms.  Moreover, the H-O-H bond angle is 104.4°.  The main idea is that this angle is less than that in NH3, due to the greater repulsions felt with two lone pairs. It is imperative to understand that lone pairs are not involved in bond formation.  They are simply in attraction with only one nucleus.  Needless to say, the lone pairs cause more repulsion.