C3.7 - Giant covalent structures

Question 1

giant covalent structures

Answer 1

huge 3D network of covalently bonded atoms

Question 2

Properties of giant covalent structures

Answer 2

• insoluble
• very high melting/boiling points
• hard (except graphite)
• cannot conduct electricity (except graphite)

Question 3

Bonding in graphite

Answer 3

-1 carbon atom is covalently bonded to 3 other C atoms
-forming hexagons - arranged in giant layers
-weak intermolecular forces between layers
+ allowing the layers to slide over each other = soft material

Question 4

delocalised electrons

Answer 4

electrons that are no longer associate with any particle

-can move around freely

Question 5

How does graphite conduct electricity

Answer 5

-as only 3 of its electrons are covalently bonded, 1 electron from each atoms is free
-so the delocalised electrons carry electrical charge
+ they move towards the positive terminal in the battery

Question 6

What happens to graphite when it conducts thermal energy?

Answer 6

• causes the delocalised electrons to move around quicker along the layers of the graphite
• energy is being transferred

Question 7

Why can diamond not conduct electricity?

Answer 7

• as all 4 of its atoms’ electrons are being used up

- it has no delocalised electrons to carry charge

Question 8

allotropes

Answer 8

different forms of the same element