How can we determine the molecular and electron geometry of H2O?
The molecular geometry deals with the position of the nucleus of the different atoms in the molecule whereas the electron geometry deals with the position of the orbitals. Electron geometry is specific for each atom in the molecule. According to VSEPR theory, valence electrons repel more than bonding electrons. This can be used to determine the geometry as we know that the oxygen atom in H2O has 2 pairs of valence electrons and 2 pairs of bonding electrons. There are therefore 4 electron domains on the oxygen atom which suggests a tetrahedral electron geometry (in order to minimise electron-electron repulsion). Because not all electron domains are counted in the molecular geometry, the shape of the molecule H2O is bent (or V-shaped).
