Summary Shapes of Molecules and Ions Notes with Labelled Diagrams

Shapes of
Molecules
and Ions
Chemistry AS1

Year 13

, Shapes of Molecules and Ions
Depends on repulsion of electrons in central atom



Electron pairs are charge clouds around an atom and aim to repel each
as far as possible



Shape is determined by:

1. Total number of electron pairs around central atom
2. Number of bonding pairs of electrons
3. Number of lone pairs of electrons



Lone pairs are more compact to the central atom – greater repulsive
effect on other pairs of electrons



Valence Shell Electron Pair Repulsion (VESPR) Theory

Theory assumes spatial arrangement of molecules and ions is
determined by the repulsion between electron pairs

It states the order of repulsion

Lone Pair - Lone Pair
Greatest
Repulsion
LP - LP

Lone Pair - Bonding Pair
LP - BP

Bonding Pair - Bonding Pair
Least
Repulsion
BP - BP




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