Giant covalent structures

Question 1

What are giant covalent structures?

Answer 1

Millions of atoms are are each joined to adjacent atoms, by covalent bonds.

Question 2

Melting/boiling points?

Giant covalent structures

Answer 2

• Solids at room temperature and have high melting points.
• This is due to their giant (LATTICE) structure, which takes a lot of energy to overcome.

Question 3

How does carbon make giant covalent structures?

Answer 3

Carbon can make 4 covalent bonds to other atoms.

Question 4

What is an allotrope?

Answer 4

Different structural forms of the same element, in the same physical state.

For carbon, and its allotropes the state is solid

Question 5

Explain the allotrope: Diamond

Answer 5

• Giant covalent structure, made up of carbon’s atoms which each form 4 bonds.
• This makes diamond very hard.
• Many covalent bonds mean that the melting point is high.
• There are no delocalised electrons, does not conduct electricity.

Question 6

Explain the allotrope: Graphite

You need to say 8.

Answer 6

• In graphite, each carbon atom makes 3/4 bonds.
• Creates layers, hexagon like.
• Between the layers, there are no covalent bonds, they are held together by a weak intermolecular force - so they can move over eachother.
• This makes graphite soft and slippery, so it is used as a lubricating material.
• It is very brittle.
• High melting point, strong covalent bonds.
• Each atom has one delocalised electron, that can move through the structure and** carry charge**.
• So it can conduct electricity.

Question 7

Explain the allotrope: Graphene

Answer 7

• One layer of graphite.
• One sheet of carbon atoms joined in hexagons.
• One atom thick.
• High melting points, due to strong covalent bonds.
• Can conduct electricity.
• Very light, can be added to composite metals to improve their strength.