Giant Covalent Structures

Question 1

Why is diamond used for the tips of drills?

[1 mark]

Answer 1

It is hard

Question 2

Nanoparticles contain a few [blank] atoms

fill in the blank

Answer 2

Nanoparticles contain a few hundred atoms

Question 3

What type of bonding does graphite have?

[1 mark]

Answer 3

Covalent

Question 4

How many carbon atoms does each carbon atom bond to in graphite

Answer 4

3

Question 5

Different types of poly(ethene) can be made by changing the conditions for the reaction

Suggest three conditions that could be changed

[3 marks]

Answer 5

1) Temperature
2) Pressure
3) Add a catalyst

Question 6

Explain why graphite is soft

[2 marks]

Answer 6

The layers in graphite have very weak forces between them

This means that the layers can freely slide over eachother, this makes graphite soft

Question 7

Explain why diamond is hard

[2 marks]

Answer 7

The carbon atoms in diamond form four covalent bonds with the other carbon atoms

These covalent bonds are very strong

Question 8

Explain why graphite can conduct electricity

Answer 8

In graphite, each carbon atom forms 3 covalent bonds with the other carbon atoms, so each carbon atom has adelocalised electrons

These delocalised electrons can move through the whole structure and carry a charge

Question 9

Explain why graphite is softer than diamond

[4 marks]

Answer 9

In graphite the layers have weak forces between them,

this means that they can freely slide over eachothe- this makes graphite soft

In diamond, the carbon atoms form four strong covalent bonds with the other carbon atoms,

this means that none of the carbon atoms are free to move and diamond is rigid

Question 10

Explain why graphite can conduct electricity and diamond cannot

[3 marks]

Answer 10

In graphite, each carbon atom, forms three covalent bonds with the other carbon atoms, so each carbon atom has a delocalised electron

These delocalised electrons can freely move through the whole structure and carry a charge,

In diamond, the carbon atoms form four covalent bonds with the other cabron atoms, so there are no delocalised electrons

Question 11

Explain why graphite is used in pencils

[2 marks]

Answer 11

The layers in graphite

have weak forces between them, which allows the layers to slide over eachother

Question 12

Give one reason why a lubricant is used when metal parts rub against eachother

[1 mark]

Answer 12

To reduce friction

Question 13

Explain why graphite is soft and slippery

[2 marks]

Answer 13

The layers in graphite

have weak forces between them, this allows the layers to freely slide over eachother, so graphite is soft and slippery

Question 14

Explain why the structures: graphite, diamond and silicon dioxide have high melting points

[2 marks]

Answer 14

The atoms in these structures are bonded by strong covalent bonds

As these bonds are strong, they require a great amount of energy to overcome, so they have a high melting point

Question 15

Silicon dioxide is used as an inside layer iside of furnaces

Suggest why

[1 mark]

Answer 15

Silicon dioxide has a very high melting point

Question 16

Explain why silicon dioxide is suitable for lining surfaces

[4 marks]

Answer 16

Silicon dioxide is a giant covalent structure, and

so it has strong covalent bonds between the atoms,

these bonds require a great amount of energy to overcome

Meaning that silicon dioxide has a high melting point