Shapes Of Molecules

Question 1

What shape of molecule has:

Total number of pairs: 2

Number of bonding pairs: 2

Number of lone pairs: 0

Answer 1

Linear

Bond angle: 180

Question 2

What shape of molecule has:

Total number of pairs: 3

Number of bonding pairs: 3

Number of lone pairs: 0

Answer 2

Trigonal planar

Bond angle: 120

Question 3

What shape of molecule has:

Total number of pairs: 3

Number of bonding pairs: 2

Number of lone pairs: 1

Answer 3

Bent

Bond angle: 118

Question 4

What shape of molecule has:

Total number of pairs: 4

Number of bonding pairs: 4

Number of lone pairs: 0

Answer 4

Tetrahedral

Bond angle: 109.5

Question 5

What shape of molecule has:

Total number of pairs: 4

Number of bonding pairs: 3

Number of lone pairs: 1

Answer 5

Trigonal pyramid

Bond angle: 107

Question 6

What shape of molecule has:

Total number of pairs: 4

Number of bonding pairs: 2

Number of lone pairs: 2

Answer 6

Bent

Bond angle: 104.5

Question 7

What shape of molecule has:

Total number of pairs: 5

Number of bonding pairs: 5

Number of lone pairs: 0

Answer 7

Trigonal bipyramid

Bond angle: 120, 90

Question 8

What shape of molecule has:

Total number of pairs: 5

Number of bonding pairs: 3

Number of lone pairs: 2

Answer 8

Trigonal planar or T shape

Bond angle: 120 or 89

Question 9

What shape of molecule has:

Total number of pairs: 6

Number of bonding pairs: 6

Number of lone pairs: 0

Answer 9

Octahedral

Bond angle: 90

Question 10

What shape of molecule has:

Total number of pairs: 6

Number of bonding pairs: 5

Number of lone pairs: 1

Answer 10

Distorted square pyramid

Bond angle: 89

Question 11

What shape of molecule has:

Total number of pairs: 6

Number of bonding pairs: 4

Number of lone pairs: 2

Answer 11

Square planar

Bond angle: 90

Question 12

What effect does a lone pair have on the bond angle?

Answer 12

Alters the bond angle by 2 degrees

Question 13

Why do molecules not appear as an expected shape?

Answer 13

The electron pair repulsion theory explains that electrons will move and arrange themselves in an order so they are as far away from other electrons as possible

Hence why water is bent and not linear

Question 14

What are the possible shapes a molecule can be if there are no lone pairs of electrons?

Answer 14

Linear

Trigonal planar

Tetrahedral

Question 15

How do you work out the number of pairs of electrons both bonded and lone in a molecule?

Answer 15

1. Number of electrons in Main central atom outer shell.
2. Number of bonds to the central atom
3. Total number of electrons (bonding and outer shell total)
4. Electron pairs (electrons / 2)
5. Number of bonding pairs
6. Number of lone pairs
7. Deduce shape

Question 16

Deduce the shape of phosphorus trihydride (PH3)

Answer 16

P has 5 electrons in outer shell

Total electrons = 5+ 3. (8)

Electrons pairs = 4. (8/2)

Bonded pairs = 3

Lone pairs = 1

Shape = trigonal pyramid bond angle 107