The molecules methane, water and ammonia illustrate the three different shapes for molecules with four electron pair domains at a central atom.
The bond geometry about these central atoms is the same in molecules containing more than one of these atoms.
Use your mouse (or tap lightly with fingers)
to rotate the JSMol objects so that you can
see all of the outer atoms and their arrangement
(geometry) about the central atom.
to rotate the JSMol objects so that you can
see all of the outer atoms and their arrangement
(geometry) about the central atom.
| molecules with one central atom  | methane (CH4) | ammonia (NH3) | water (H2O) |
| bond geometry | tetrahedral | trigonal pyramidal | bent |
The bond geometry about these central atoms is the same in molecules containing more than one of these atoms.
Rotate the models (both above and below) to convince yourself that in the molecules below, the geometry of bonds at
C bonded to four atoms is the same as at C in CH4
N bonded to three atoms is the same as at N in NH3
O bonded to two atoms is the same as at O in H2O.
N bonded to three atoms is the same as at N in NH3
O bonded to two atoms is the same as at O in H2O.
| Molecules with multiple central atoms | |||
| Number/ type of central atoms | three carbons | two carbons one nitrogen | two carbons one oxygen |
| Bond geometry at each central atom | two tetrahedral (4 domains) one trigonal planar (3 domains) | two C tetrahedral (4 domains) N trigonal pyramidal (4 domains - 1 nbp) | two C tetrahedral (4 domains) O bent (4 domains - 2 nbp) |