A bond dipole is only part of the story.
Electron regions arrange to reduce repulsion. Two regions give a linear arrangement, three trigonal planar and four tetrahedral. With four regions, one lone pair gives a trigonal pyramidal molecule and two lone pairs give a bent molecule. Lone pairs tend to compress bond angles.
Molecular polarity depends on vector addition of bond dipoles. CO₂ has polar bonds but their equal opposite dipoles cancel in a linear molecule. Water is bent, so its bond dipoles do not cancel. Identical surrounding atoms and symmetry are important when deciding cancellation.
Two bond dipoles add
Explore the relationship
Two equal dipoles: they cancel at 180° but not in a bent arrangement. This model is not a full VSEPR energy calculation.
Tap or focus a plotted point to read its values.
View plotted data as a table
| Series | Angle between identical bonds / degrees | Resultant dipole magnitude |
|---|---|---|
| Resultant dipole magnitude | 90 | 1.41421 |
| Resultant dipole magnitude | 91.5 | 1.39558 |
| Resultant dipole magnitude | 93 | 1.37671 |
| Resultant dipole magnitude | 94.5 | 1.3576 |
| Resultant dipole magnitude | 96 | 1.33826 |
| Resultant dipole magnitude | 97.5 | 1.31869 |
| Resultant dipole magnitude | 99 | 1.2989 |
| Resultant dipole magnitude | 100.5 | 1.27888 |
| Resultant dipole magnitude | 102 | 1.25864 |
| Resultant dipole magnitude | 103.5 | 1.23819 |
| Resultant dipole magnitude | 105 | 1.21752 |
| Resultant dipole magnitude | 106.5 | 1.19665 |
| Resultant dipole magnitude | 108 | 1.17557 |
| Resultant dipole magnitude | 109.5 | 1.15429 |
| Resultant dipole magnitude | 111 | 1.13281 |
| Resultant dipole magnitude | 112.5 | 1.11114 |
| Resultant dipole magnitude | 114 | 1.08928 |
| Resultant dipole magnitude | 115.5 | 1.06723 |
| Resultant dipole magnitude | 117 | 1.045 |
| Resultant dipole magnitude | 118.5 | 1.02259 |
| Resultant dipole magnitude | 120 | 1 |
| Resultant dipole magnitude | 121.5 | 0.977242 |
| Resultant dipole magnitude | 123 | 0.954318 |
| Resultant dipole magnitude | 124.5 | 0.931229 |
| Resultant dipole magnitude | 126 | 0.907981 |
| Resultant dipole magnitude | 127.5 | 0.884577 |
| Resultant dipole magnitude | 129 | 0.861022 |
| Resultant dipole magnitude | 130.5 | 0.837319 |
| Resultant dipole magnitude | 132 | 0.813473 |
| Resultant dipole magnitude | 133.5 | 0.789488 |
| Resultant dipole magnitude | 135 | 0.765367 |
| Resultant dipole magnitude | 136.5 | 0.741115 |
| Resultant dipole magnitude | 138 | 0.716736 |
| Resultant dipole magnitude | 139.5 | 0.692234 |
| Resultant dipole magnitude | 141 | 0.667614 |
| Resultant dipole magnitude | 142.5 | 0.642879 |
| Resultant dipole magnitude | 144 | 0.618034 |
| Resultant dipole magnitude | 145.5 | 0.593083 |
| Resultant dipole magnitude | 147 | 0.568031 |
| Resultant dipole magnitude | 148.5 | 0.542881 |
| Resultant dipole magnitude | 150 | 0.517638 |
| Resultant dipole magnitude | 151.5 | 0.492307 |
| Resultant dipole magnitude | 153 | 0.466891 |
| Resultant dipole magnitude | 154.5 | 0.441395 |
| Resultant dipole magnitude | 156 | 0.415823 |
| Resultant dipole magnitude | 157.5 | 0.390181 |
| Resultant dipole magnitude | 159 | 0.364471 |
| Resultant dipole magnitude | 160.5 | 0.338699 |
| Resultant dipole magnitude | 162 | 0.312869 |
| Resultant dipole magnitude | 163.5 | 0.286985 |
| Resultant dipole magnitude | 165 | 0.261052 |
| Resultant dipole magnitude | 166.5 | 0.235075 |
| Resultant dipole magnitude | 168 | 0.209057 |
| Resultant dipole magnitude | 169.5 | 0.183003 |
| Resultant dipole magnitude | 171 | 0.156918 |
| Resultant dipole magnitude | 172.5 | 0.130806 |
| Resultant dipole magnitude | 174 | 0.104672 |
| Resultant dipole magnitude | 175.5 | 0.0785196 |
| Resultant dipole magnitude | 177 | 0.0523539 |
| Resultant dipole magnitude | 178.5 | 0.0261792 |
| Resultant dipole magnitude | 180 | 1.22465e-16 |
Explore: Compare equal bond dipoles at 180° and at a bent angle.
Predict shape and polarity of water.
- Oxygen has two bonding regions and two lone pairs: four regions total.
- The molecular shape is bent, approximately 104.5°, and the dipoles do not cancel.
Assumed knowledge
Lewis structures and electronegativity.
Learning checkpoints & source
YOUR LEARNING CHECKPOINT- Use VSEPR to predict shapes and approximate bond angles.
- Determine molecular polarity from shape and bond dipoles.