Electron Domains | Arrangement of Electron Domains | General Molecular Formula1 | Molecular Shape2 | Examples | Hybrid Orbitals3 | Polar?4 |
---|---|---|---|---|---|---|
2 |
Linear |
AX2 |
Linear |
CO2 |
sp |
No |
3 |
AX3 |
Trigonal planar |
BF3, AlCl3 |
sp2 |
No |
|
|
|
AX2E |
Angular |
SnCl2 |
|
Yes |
4 |
AX4 |
Tetrahedral |
CH4, SiCl4 |
sp3 |
No |
|
|
|
AX3E |
Trigonal pyramidal |
NH3, PCl3 |
|
Yes |
|
|
AX2E2 |
Angular (Bent) |
H2O, SCl2 |
|
Yes |
5 |
AX5 |
Trigonal bipyramidal |
PCl5, AsF5 |
dsp3 |
No |
|
|
|
AX4E |
Disphenoidal |
SF4 |
|
Yes |
|
|
AX3E2 |
T-shaped |
ClF3 |
|
Yes |
|
|
AX2E3 |
Linear |
XeF2 |
|
No |
6 |
AX6 |
Octahedral |
SF6 |
d2sp3 |
No |
|
|
|
AX5E |
Square pyramidal |
BrF5 |
|
Yes |
|
|
AX4E2 |
Square planar |
XeF4 |
|
No |
1 For the General Molecular Formula, "A" refers to central atom, "X" refers to atoms attached to central atom, and "E" refers to unbonded electron pairs. For example, AX2E2 is shown as the formula for water (H2O), which has two bonded hydrogen atoms ("X") and two lone (unbonded) electron pairs ("E").
2 For compounds containing 5 pairs of electrons (bonding and/or lone pairs), all lone pairs are placed in the trigonal planar electron region, never above or below the trigonal planar region. This arrangement maximizes the separation of lone electron pairs to their neighbors. See the Trigonal bipyramidal(five domains) webpage for diagrams.
3 For Hybrid Orbitals, you can always know the VSEPR electron arrangement (see Arrangement of Electron Domains column). Molecular Geometry is based on the arrangement of the bonded atoms, according to the General Molecular Formula column.
4 For molecules that contain the same attached atoms, a symmetrical molecule is not polar. An assymetrical molecule (non-symmetrical electron domains) is polar if the individual bonds are polar.
Copyright © Dr. Donald L. Robertson (Modified: 01/27/2010)