Bonding and structure- shape of molecules

Question 1

What shape occurs when there are 2 bonding pairs and no lone pairs?

Answer 1

Linear

Question 2

What is the bond angle in linear molecules?

Answer 2

180

Question 3

Give an example of a substance with a linear shape

Answer 3

BeF2

Question 4

What shape occurs when there are 3 bonding pairs and no lone pairs?

Answer 4

Trigonal planar

Question 5

What shape occurs when there are 4 bonding pairs and no lone pairs?

Answer 5

Tetrahedral

Question 6

What shape occurs when there are 3 bonding pairs and 1 lone pair?

Answer 6

Trigonal pyramid

Question 7

What shape occurs when there are 2 bonding pairs and 2 lone pairs?

Answer 7

Bent/v-shape

Question 8

What shape occurs when there are 5 bonding pairs and no lone pairs?

Answer 8

Trigonal bipyramid

Question 9

What shape occurs when there are 6 bonding pairs and no lone pairs?

Answer 9

Octahedral

Question 10

What is the bond angle in trigonal planar?

Answer 10

120

Question 11

What is the bond angle in tetrahedral?

Answer 11

109.5

Question 12

What is the bond angle in bent/v-shaped?

Answer 12

104.5

Question 13

What is the bond angle in trigonal pyramid?

Answer 13

107

Question 14

What is the bond angle in octahedral?

Answer 14

90

Question 15

What is the bond angle in trigonal bipyramid?

Answer 15

90 and 120

Question 16

Give an example of a molecule which has as octahedral shape?

Answer 16

SF6

Question 17

Give an example of a molecule which has a trigonal bipyramidal shape

Answer 17

PF5

Question 18

Give an example of a molecule which has a trigonal pyramid shape

Answer 18

NH3

Question 19

Give an example of a molecule which has a trigonal planar shape

Answer 19

BH3

Question 20

Relative to single bonds, how much do double bonds repel?

Answer 20

Equally

Question 21

What shape of bonding is present in Carbon dioxide?

Answer 21

Linear

Question 22

When representing an ion in 3D what must you remember to draw?

Answer 22

Square brackets around the structure and the charge in the top right corner outside the brackets

Question 23

Explain why NH3 has a different shape to BH3

Answer 23

• BH3 does not have any lone pairs so has a bond angle of 120
• NH3 has one lone pair
• Lone pairs repel more the bonding pairs so the atoms are pushed into a trigonal pyramid shape

Question 24

What conditions are needed for a bond to be non-polar?

Answer 24

• the bonding atoms to be the same

- the bonded atoms have the same or similar electronegativity

Question 25

What happens to the electron pair in a non-polar bond?

Answer 25

The bonded pair is shared equally between the bonded atoms

Question 26

What kind of dipole is present in a polar covalent bond?

Answer 26

A PERMANENT dipole

Question 27

What would you look for in a molecule to tell if it has a polar bond?

Answer 27

A delta charge a difference in electronegativity values the presence of N, O, F, or Cl

Question 28

In addition to having polar bonds, molecules with a dipole must have what other property?

Answer 28

Asymmetry in the arrangement of the atoms

Question 29

What are the 3 types of intermolecular forces?

Answer 29

- London forces (temporary dipole-dipole interactions) - Permanent dipole-dipole interactions - Hydrogen bonds

Question 30

What is the order of relative strength of intermolecular forces from weakest to strongest?

Answer 30

- London forces - Permanent dipole-dipole interactions - Hydrogen bonding

Question 31

What does hydrogen bonding occur between?

Answer 31

The lone pair of an electronegative element and a hydrogen atom attached to an electronegative atom

Question 32

What is the shape around the hydrogen atom involved in the hydrogen bond?

Answer 32

linear

Question 33

What are the 3 anomalous properties of water?

Answer 33

1) High melting and boiling point compared to similar molecules 2) Expansion on freezing (The solid is less dense than the liquid) 3) High surface tension

Question 34

How many hydrogen bonds can a water molecule form?

Answer 34

4

Question 35

Why can a water molecule form 4 hydrogen bonds?

Answer 35

- it has 2 lone pairs on the oxygen | - it has 2 hydrogen atoms

Question 36

Why does ice float on water?

Answer 36

- Hydrogen bonds in ice hold water molecules apart in an open lattice structure - Water molecules in ice are further apart than in water - Solid ice is less dense than liquid water and floats