16. Rules for working out shapes - Molecules with LONE PAIRS

Why do lone pairs affect the shape?

Lone pairs have larger repulsive effect than bonded pair and distorts shape of molecule and reduces bond angle

Describe the charge cloud for a bonding pair?

Sausage shaped as electrons attracted to 2 different nuclei

Describe the charge cloud for a lone pair

Football shaped as electrons pulled closer to nucleus of the central ato

What do lone pairs exert?

Exert the greatest effect -> Orbital of lone pair of electrons is concentrated closer to nucleus of central atom

What is the order of repulsive strength?

Lone pair-lone pair > Lone pair-bond pair > bond pair-bond pair

Give an example of a molecule with a lone pair?

NH₃ -> 3 bonding pairs and 1 lone pair

Draw NH₃

Yes

Why do lone pairs have a greater repulsive effect?

Lone pairs are concentrated closer to the nucleus of the central atom than bonding pairs

What happens due to lone pairs being concentrated closer to the nucleus of the central atom?

Exercise greater repulsive effect

What happens due to the greater repulsive effect caused by lone pairs?

Close up angles between bonding pairs of electrons making it 107.4

What do we call the NH₃ Shape?

Pyrimidal

Draw H₂O

Yes

What is the shape with 2 lone pairs?

Bent

Compare 2 lone pairs to 1 lone pair?

Exert greater repulsive effect so bond angle closes more to 104.5