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. The higher the number of lone pairs, the higher the repulsion and the more the bonding angle is reduced (this is because they want to minimise repulsion).

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?