Topic 2: Bonding angles

What is special about bigger atoms about bigger atoms, allowing to form more bonding pairs?

Bigger atoms can expand their octet

How is the shape of a molecule determined?

The shape of a molecule is determine by the number of lone pairs, electron pairs arranged to minimise repulsion. The higher the number of lone pairs → the greater the lone pair - bond pair repulsion than bond pair- bond pair repulsion → and the more the bonding angle is reduced.

How do you calculate number of lone pairs on a bonded atom and how do you calculate total number of electron pairs respectively?

Calculations:

1. Use 0.5(number of outer shell electrons on central atom - number of atoms bonded to central atom) to calculate number of lone pairs

2. Use bonding pairs + lone pair, to find out total electron pairs

Electron pairs: 2 Number of bonding pairs: 2 Number of lone pairs: 0

Shape?

Electron pairs: 3 Number of bonding pairs: 3 Number of lone pairs: 0

Shape?

Electron pairs: 3 Number of bonding pairs: 2 Number of lone pairs: 1

Shape?

Electron pairs: 4 Number of bonding pairs: 4 Number of lone pairs: 0

Shape?

Electron pairs: 4 Number of bonding pairs: 3 Number of lone pairs: 1

Shape?

Electron pairs: 4 Number of bonding pairs: 2 Number of lone pairs: 2

Shape?

Electron pairs: 5 Number of bonding pairs: 5 Number of lone pairs: 0

Shape?

Electron pairs: 5 Number of bonding pairs: 4 Number of lone pairs: 1

Shape?

Electron pairs: 5 Number of bonding pairs: 3 Number of lone pairs: 2

Shape?

Electron pairs: 6 Number of bonding pairs: 6 Number of lone pairs: 0

Shape?

Electron pairs: 6 Number of bonding pairs: 5 Number of lone pairs: 1

Shape?

Electron pairs: 6 Number of bonding pairs: 4 Number of lone pairs: 2

Shape?