BRAINCAKEElectron Pair Repulsion Theory
The electron pair repulsion theory can be used to predict the shape and bond angles of covalent molecules and polyatomic ions.
Electron pairs repel each other so they are arranged as far apart as possible. This minimises repulsion and holds the molecule in a particular shape.
The shape of a molecule depends on the number of electron pairs.
A lone pair of electrons is slightly closer to the central atom and therefore takes up more space than a bonded pair of electrons. As a result, repulsion from a lone pair is stronger than from a bonding pair. For each lone pair, the bond angle decreases by about 2.5°
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Key terms in this lesson
- Atomic orbital
- A region in space around the nucleus where there is a 95% probability of finding an electron of a given energy.
- Lone pair
- A pair of outer-shell electrons that is not involved in bonding.
- Period
- A horizontal row of the periodic table, containing elements with the same number of electron shells.
More in Bonding
- Van der Waals forces
- Hydrogen Bonding
- Boiling Point of Hydrides
- The Importance of Hydrogen Bonding
- Two Pairs of Electrons
- Three Pairs of Electrons
- Four Pairs of Electrons
- Five Pairs of Electrons
All 30 lessons in Bonding · All AQA AS-level Chemistry topics