Examples
[PO4]3−
| Central atom: | P |  |
|---|---|---|
| P contributes: | 5 e− | |
| 4 x O contibute: | 8 e− | |
| 3 x -ve charge: | 3 e− | |
| Total VSE: | 16 | |
| Total VSEP: | 8 | |
| 4 x double bonds | − 4 pairs | |
| Revised Total: | 4 | |
| Geometry: | Tetrahedral | |
Notes
- O=P=O bond angle = 109°
- The phosphate ion is of vital importance in biological systems. DNA is a phosphate ester as are ATP and ADP (chemicals used to store and release energy in biological systems). The phosphate ion also makes up about two-thirds by mass of our teeth and bones.