Macromolecules

Question 1

diamond

Answer 1

• each carbon atom is covalently bonded to four other carbon atoms
• these bonds are extremely strong, making diamonds the hardest natural substance
• it is used in cutting tools

Question 2

graphite

Answer 2

• each carbon atom is covalently bonded to three carbon atoms
• this forms layers of hexagons
• there are weak forces of attraction between the layers and therefore they can slide over each ither, making graphite soft
• has delocalised electrons: good conductor of electricity
• used as electrodes and lubricants

Question 3

silicon (IV) oxide

Answer 3

every silicon is covalently bonded to 4 oxygen atoms. each oxygen atom is covalently bonded to two silicon atoms. the structure is very silar to the structure of diamond

Question 4

why does diamond/ graphite have such a high melting point

Answer 4

• giant covalent structure

- many strong covalent bonds which require a largw input of energy to break

Question 5

why does graphite conduct electricity and diamond does not?

Answer 5

in graphite each carbon atom is only bonded to 3 others, so the 4th electron is delocalised and can carry the charge

in diamond there is no such free electron

Question 6

why is graphite used as a lubricant?

Answer 6

• carbon atoms are arranged in layers
• layers are held together by weak intermolecular forces
• do not require a lot of energy to break
• layers can slide between each other