Shapes

Question 1

What 7 things do you do to work out the shape?

Answer 1

Draw dot and cross diagram
Count areas of electron density
Decide basic shape (no lone pairs)
Draw diagram of the shape
State the number of bonding/lone pairs
Always say electron pairs repel for maximum separation
If lone pairs say lone pairs repel more than bonding pairs

Question 2

What is the shape of the molecule is there are 2 bonding pairs?

Answer 2

Linear

180 degrees

Question 3

What is the shape of the molecule is there are 3 bonding pairs?

Answer 3

Trigonal planar

120 degrees

Question 4

What is the shape of the molecule is there are 4 bonding pairs?

Answer 4

Tetrahedral

109.5 degrees

Question 5

What is the shape of the molecule is there are 5 bonding pairs?

Answer 5

Trigonal bipyramidal

90 degrees AND 120 degrees`

Question 6

What is the shape of the molecule is there are 6 bonding pairs?

Answer 6

Octahedral

90 degrees

Question 7

How much do lone pairs decrease the bond angle by?

Answer 7

2.5 degrees every lone pair

Question 8

What is the shape of the molecule is there are 3 bonding pairs and 1 lone pair?

Answer 8

Pyramidal

107 degrees

Question 9

What is the shape of the molecule is there are 2 bonding pairs and 2 lone pairs?

Answer 9

Non-linear

104.5 degrees

Question 10

What is electronegativity?

Answer 10

Ability of an atom to attract a pair of electrons in a covalent bond.

Question 11

What happens to electronegativity as you go across the groups?

Answer 11

Electronegativity increases

Question 12

What happens to electronegativity as you go down the group?

Answer 12

Electronegativity decreases

Question 13

What does the difference in electronegativity tell you?

Answer 13

The type of bond
0-0.4 = covalent
0.4-1.8 = polar covalent
More than 1.8 = ionic