# The electron pair geometry of a molecule is tetrahedral. What is its bond angle if it shows one lone pair of electrons and three bonding pairs?

If there are 4 electron pairs around a central atom, ideally the angle is tetrahedral. In a real molecule, the angle be compressed from 109.5""^@.
VSEPR predicts that the electron pairs will be arranged in a tetrahedron. However, because we describe the geometry on the basis of the disposition of atoms, not electron pairs, the symmetry descends to trigonal pyramidal. The structure would be the equivalent of ammonia, with bond angles approx. 105""^@. The lone pair is stereochemically active. Examine the structures and bond angles of both ammonia and water.