3.2 Shapes of Molecules

Question 1

What do the Shapes of Molecules depend on?

Answer 1

The shape of a molecule depends on the number of groups of electrons.

Question 2

What could a group of electrons be?

Answer 2

A group of electrons could be a bonding pair, two bonding pairs, three bonding pairs or a lone pair.

Question 3

What do groups of electrons do to each other?

Answer 3

Groups of electrons repel each other

Question 4

How do groups of electrons arrange each other?

Answer 4

Groups of electrons will arrange themselves so as to be as far apart in space as possible.

Question 5

Four Groups of Electrons Four Groups of electrons: 109

Answer 5

1. Tetrahedral (4 bonding pairs)
2. Pyramidal (3 bonding pairs, 1 lone pair)
3. Bent (2 bonding pairs 2 lone pairs)

Question 6

Methane

Answer 6

Methane—Tetrahedral (4 bonding pairs)
Four groups of electrons around the central carbon atom.
Four covalent bonding pairs.
Similar charges repel.
Groups arrange themselves as far apart as possible

Question 7

Lone pairs

Answer 7

Repel the bonding pairs of electrons.

Question 8

Three Groups of Electrons: Bond angles of 120

Answer 8

1. Planar Triangular

Eg. Ethene: 2 bonding pairs and 1 double bond

Question 9

Two Groups of Electrons: 180

Answer 9

1. Linear

Question 10

What are Octahedral atoms? What is their bond angle?

Answer 10

Octahedral molecules: Six groups of electrons around a central atom
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