C2- Structure & bonding

Question 1

why do elements form bonds?

Answer 1

to get a full outer shell of electrons

Question 2

state the three types of bonding

Answer 2

covalent, ionic and metallic bonding

Question 3

describe covalent bonding

Answer 3

where non-metal atoms share pairs of electrons

Question 4

describe ionic bonding

Answer 4

1. where a metal atom loses electrons which are gained by a non-metal atom
2. these oppositely charged ions are attracted to each other

Question 5

describe metallic bonding

Answer 5

1. where metal atoms lose electrons.

2. the positive metal ions are attracted to the delocalised electrons around them.

Question 6

in covalent bonding, the number of bonds formed is always the…

Answer 6

same as the number of electrons needed for a full outer shell

Question 7

covalent bonds can be…

Answer 7

(1) giant structures

(2) small molecules

Question 8

why do giant structures have high melting/boiling points?

Answer 8

because lots of energy is needed to break the strong covalent bonds

Question 9

why do small molecules have low melting/boiling points?

Answer 9

because not much energy is needed to break the weak intermolecular bonds between molecules

Question 10

do covalent bonds conduct electricity? why?

Answer 10

No.

covalent bonds don’t have an overall electric charge (no mobile ions or electrons)

Question 11

what are ions?

Answer 11

charged atoms or groups of atoms

Question 12

how do atoms become ions?

Answer 12

by gaining/losing electrons

Question 13

metal atoms lose electrons to…

Answer 13

form positive ions

Question 14

non-metals gain electrons to…

Answer 14

form negative ions

Question 15

why do giant ionic lattices have high melting/boiling points?

Answer 15

because lots of energy is needed to break the strong ionic bonds

Question 16

what are the properties of ionic bonds?

Answer 16

1. don’t conduct electricity as a solid

2. do conduct electricity when molten (liquid) or dissolved in water

Question 17

why don’t ionic bonds conduct electricity when solid?

Answer 17

because the ions can’t move (immobile) so no charge can flow

Question 18

why can ionic bonds conduct electricity when molten?

Answer 18

because the ions are mobile so a charge can flow throughout the structure

Question 19

what are the strengths of using the dot & cross model?

Answer 19

1. shows electrons gained/ lost

2. shows charge

Question 20

state a weakness of using the dot & cross model

Answer 20

it doesn’t show lattice structure

Question 21

what are the strengths of using a 2D model?

Answer 21

1. partially shows the lattice structure

2. shows charge

Question 22

state the weaknesses of using a 2D model

Answer 22

1. doesn’t show electrons

2. hard to see 3D structure

Question 23

what are the strengths of using the ball & stick model?

Answer 23

1. shows lattice structure

2. shows charge

Question 24

state the weaknesses of using the ball & stick model

Answer 24

1. doesn’t show electrons gained/lost

2. gaps between ions are unrealistic

Question 25

state 3 properties of metals

Answer 25

(1) high melting/ boiling points
(2) can be bent/ shaped
(3) can conduct electricity

Question 26

why do metals have high melting/boiling points?

Answer 26

because lots of energy is needed to break the strong metallic bonds

Question 27

why can metals be bent/shaped?

Answer 27

because the metal ions are in layers which can slide over each other

Question 28

why can metals conduct electricity?

Answer 28

because they have delocalised electrons which can carry a charge throughout the structure