How do you find the geometry of #SiH_4# using the VSEPR method?

1 Answer
Dec 30, 2016

There are 4 valence electrons for #Si#, and the 4 valence electrons from #H#. A tetrahedral geometry is described.


Given that silicon has 4 valence electrons, and each hydrogen contributes 1 electron, there are 8 valence electrons, and thus there are 4 electron pairs to be distrbuted around the central silicon atom.

And if there are 4 electron pairs, the geometry is based on a tetrahedron, i.e. each #/_H-Si-H=109.5^@#.

And thus silane, #SiH_4#, has a tetrahedral geometry.

Note that you probably know the geometry of methane, #CH_4#. Because silicon has precisely the same valence orbitals as carbon, the geometry of silane is an analogue.