Structure and Bonding

Question 1

what is ionic bonding between?

Answer 1

a metal and a non-metal

Question 2

what is the aim of ionic bonding?

Answer 2

both elements achieve a full outer energy level

Question 3

what are giant ionic lattices? (2)

Answer 3

• where every positive ion is surrounded by negative ions
• have strong forces of attraction between the positive and negative ions (electrostatic forces)

Question 4

the two key points about ionic compounds:

Answer 4

1. have very high melting and boiling points

because the strong electrostatic forces require a great deal of energy to break

2. can not conduct electricity when they are solids

because the ions can not move - they are locked in place by the strong electrostatic forces of attraction

Question 5

what is covalent bonding between?

Answer 5

a non-metal and a non-metal

Question 6

define covalent bonding

Answer 6

sharing an electron, or electrons, to achieve a full outer energy level

Question 7

two key properties of small covalent molecules:

Answer 7

1. have low melting and boiling points

because there are weak intermolecular forces between the molecules that do not require a great deal of energy to break

2. they are usually gases or liquids at room temperature
3. do not conduct electricity

because the molecules do not have an overall electric charge

Question 8

two key properties of giant covalent molecules:

Answer 8

1. always solids at room temperature

because they have millions of strong covalent bonds

2. always have high melting and boiling points

Question 9

which element is diamond formed from?

Answer 9

carbon

Question 10

key properties of diamond: (3)

Answer 10

1. each carbon atom forms four strong covalent bonds
2. diamonds have a huge number of strong covalent bonds and these have to be broken when diamond is melted

this requires a great deal of energy

3. diamond can not conduct electricity

there are no free electrons to carry electrical charge

Question 11

key properties of silicon dioxide:

Answer 11

1. has a very high melting and boiling point

because it has a huge number of strong covalent bonds that need to be broken and this requires a great deal of energy

Question 12

two examples of giant covalent molecules?

Answer 12

diamond
silicon dioxide

Question 13

what are the three properties of graphite?

Answer 13

• has a high melting and a boiling point
• soft and slippery
• an excellent conductor of both electricity and heat

Question 14

which element is graphite formed from?

Answer 14

carbon

Question 15

how many bonds does each carbon atom form in graphite?

Answer 15

three covalent bonds

Question 16

why does graphite have a high melting and boiling point?

Answer 16

because it has many strong covalent bonds and so it takes a great deal of energy to break these

Question 17

why is graphite slippery? (2)

Answer 17

• the hexagonal rings are in layers
• there are no covalent bonds between the layers and so they can slide

Question 18

why is graphite a good conductor of heat and electricity?

Answer 18

because it has a sea of delocalised electrons that can move freely

Question 19

what is graphene? (2)

Answer 19

• a single layer of graphite
• one atom thick

Question 20

what are the properties of graphene? (2)

Answer 20

• excellent conductor of electricity because it has delocalised electrons
• graphene is extremely strong

Question 21

what are fullerenes? (3)

Answer 21

• molecules of carbon atoms with hollow shapes
• usually have hexagonal rings of carbon atoms
• can also have rings with five or seven carbon atoms

Question 22

what was the name of the first fullerene to be discovered?

Answer 22

buckminsterfullerene

Question 23

what are the uses of fullerenes? (3)

Answer 23

• pharmaceutical delivery
• lubricants
• catalysts

Question 24

what are the properties of carbon nanotubes? (2)

Answer 24

• have high tensile strength ( can be stretched without breaking)
• excellent conductors of heat and electricity

Question 25

what are the uses of carbon nanotubes?

Answer 25

• used to reinforce materials e.g. in tennis rackets

Question 26

what are polymers?

Answer 26

very large molecules - made by joining together thousands of small, identical molecules (monomers)

Question 27

what are the key properties of polymers?

Answer 27

• most are solids at room temperature because the intermolecular forces of attraction between polymer molecules are relatively strong

Question 28

what is the key property of a metal?

Answer 28

• they can be bent and shaped because in metals, the layers of atoms are able to slide over each other

Question 29

what is an alloy?

Answer 29

a mixture of metals

Question 30

what is the key property of of alloys? (2)

Answer 30

• the different sizes of atoms distorts the layers, making it more difficult for them to slide over each other
• alloys are harder than pure metals