EL5b - Shapes of Molecules

Question 1

Groups of electrons ____ each other

Answer 1

repel

Question 2

In order to minimise the repulsion between groups of electrons, how do they arrange themselves?

Answer 2

As far apart as possible

Question 3

What do we call a non-bonding pair of electrons?

Answer 3

A lone pair

Question 4

What is the name of the shape formed by two bonds at 180 degrees?

Answer 4

Linear

Question 5

What is the name of the shape made by three bonds?

Answer 5

Trigonal planar

Question 6

What does planar mean?

Answer 6

All atoms are in the same plane

Question 7

What is the maximum repulsion between 3 bonded electron groups?

Answer 7

120 degrees

Question 8

What is the shape made by four bonds?

Answer 8

Tetrahedral

Question 9

What is the maximum repulsion between 4 bonded electron groups?

Answer 9

109.5

Question 10

What shape do 5 bonds form?

Answer 10

Trigonal bipyramid

Question 11

What are the 2 sets of bond angles in a trigonal bipyramid?

Answer 11

120 between atoms in the equatorial triangle

90 between equatorial and axial atoms

Question 12

What shape do 6 bonds form? What is the bond angle?

Answer 12

Octahedral

90

Question 13

Each lone pair reduces the bonding angle by how many degrees?

Answer 13

2.5

Question 14

What shape and angle is formed by 2 bonding groups and a lone pair?

Answer 14

Bent

117.5

Question 15

What shape and angle is formed by 3 bonding groups and a lone pair?

Answer 15

Trigonal pyramidal

107

Question 16

What shape and angle is formed by 2 bonding groups and 2 lone pairs?

Answer 16

Bent

104.5

Question 17

What does VSEPR stand for?

Answer 17

Valence Shell Electron Pair (group) Repulsion

Question 18

What shape is carbon dioxide?

Answer 18

Linear 180

Question 19

Model answer for why molecule is a certain shape

4 points

Answer 19

Number of electron groups
How many bonding how many lone pairs
Mentions electron groups repel each other
Uses exact phrase ‘electron groups will be arranged as far as possible apart in order to minimise repulsion’

Question 20

Explain the shape of a water molecule

• how many groups
• how many bonding + lone
• explain repulsion
• state shape and angle

Answer 20

• 4 electron groups surrounding oxygen
• 2 bonding 2 lone pairs
• electron groups repel each other, lone pairs repel more than bonded groups
• electron groups will be arranged as far as possible apart in order to minimise repulsion
• shape is bent and bond angle is 104.5

Question 21

4 bonding groups and one lone pair gives what shape?

Answer 21

Seesaw

Question 22

3 bonding groups and 2 lone pairs is what shape?

Answer 22

T shape

Question 23

2 bonding groups and 3 lone pairs has what shape and angle?

Answer 23

Linear 180