The geometry about an atom in an organic molecule is consistent with Valence Shell Electron Pair Repulsion (VSEPR) Theory. This theory predicts the geometry bonds about an atom by assuming that the electron pair domains at that atom occupy positions as far apart as possible.
There are two types of electron pair domains.
Bonding electron pair domains may contain one or more bonding electron pairs.
Nonbonding electron pair domains each have one nonbonding electron pair.
The various shape descriptors are shown below for the atoms of type AXn where the sum of the number of bonded atoms and the number of non-bonding pairs at A is either three or four. X is an atom bonded to A, and E is a nonbonding electron pair at A.
The representations above indicate the three-dimensional arrangement of the bonds. Those atoms joined to the central atom by
Bonding electron pair domains may contain one or more bonding electron pairs.
Nonbonding electron pair domains each have one nonbonding electron pair.
The various shape descriptors are shown below for the atoms of type AXn where the sum of the number of bonded atoms and the number of non-bonding pairs at A is either three or four. X is an atom bonded to A, and E is a nonbonding electron pair at A.
| AX3 | AX4 | AX3E | AX2E2 | |
 |  |  |  | |
| trigonal planar | tetrahedral | trigonal pyramid | bent | |
| Example: A = each carbon in H2C=CH2 | Example: A = each carbon in CH3CH2CH3 | Example: A = N in CH3NH2 | Example: A = O in CH3OH |
The representations above indicate the three-dimensional arrangement of the bonds. Those atoms joined to the central atom by
a solid line are in the plane of the screen.
a solid wedge point to atoms in front of the plane of the screen.
a hashed wedge point to atoms behind the plane of the screen.
a solid wedge point to atoms in front of the plane of the screen.
a hashed wedge point to atoms behind the plane of the screen.