2.7 - Diamond & Graphite

Question 1

What are two substances made from the same element, that are in the same physical state, but that have different structures?

Answer 1

Two substances made from the same element, that are in the same physical state, but that have different structures, are called allotropes.

Question 2

Select two allotropes of solid carbon from this list:

1. Diamond
2. Silicon dioxide
3. Carbon dioxide
4. Graphite

Answer 2

1. Diamond & 4. Graphite

Question 3

tiny / giant / lattice / cube / carbon / silicon

Diamond and graphite are examples of _____ covalent molecular structures.

Both are made from the element _______ arranged into a large regular repeating _____.

Answer 3

Diamond and graphite are examples of giant covalent molecular structures.

Both are made from the element carbon arranged into a large regular repeating lattice.

Question 4

Which of the following statements are true of diamond?

1. It conducts electricity
2. It is made up of silicon and oxygen
3. Each carbon atom is bonded to 3 other carbon atoms
4. Each carbon atom is bonded to 4 other carbon atoms

Answer 4

4. Each carbon atom is bonded to 4 other carbon atoms

Question 5

If there was a structure with each carbon atom bonded to 4 other carbon atoms, what structure would that be?

1. Glass
2. Carbon
3. Graphite
4. Diamond

Answer 5

4. Diamond

Question 6

If there was a structure with each carbon atom bonded to 3 other carbon atoms, what structure would that be?

1. Glass
2. Carbon
3. Graphite
4. Diamond

Answer 6

3. Graphite

Question 7

In diamond, each ______ atom is bonded to _ other atoms via covalent bonds.

This forms a regular 3D lattice which is very s_____, and has very high melting and boiling points.

Answer 7

In diamond, each carbon atom is bonded to 4 other atoms via covalent bonds.

This forms a regular 3D lattice which is very strong, and has very high melting and boiling points.

Question 8

Can diamond conduct electricity, why or why not?

Answer 8

No, in diamond, each carbon is bound to 4 other carbon atoms. This means there are no free electrons to carry charge, so it cannot conduct electricity.

Question 9

Unlike diamond, the carbon atoms in graphite each bond to _ other carbon atoms.

This arranges the graphite into 2D layers made up of repeating _______.

Answer 9

Unlike diamond, the carbon atoms in graphite each bond to 3 other carbon atoms.

This arranges the graphite into 2D layers made up of repeating hexagons.

Question 10

able / unable / localised / delocalised

Graphite is ______ to conduct electricity.

This is because each carbon atom has one __________ electron, which can move freely, and so is able to carry charge.

Answer 10

Graphite is able to conduct electricity.

This is because each carbon atom has one delocalised electron, which can move freely, and so is able to carry charge.

Question 11

Graphite is a lot ______ than diamond.

This is because the 2D layers of graphite stack on top of each other with only weak ____________ forces holding them together.

This means the layers can slide over each other, making graphite ______ to break.

Answer 11

Graphite is a lot softer than diamond.

This is because the 2D layers of graphite stack on top of each other with only weak intermolecular forces holding them together.

This means the layers can slide over each other, making graphite easier to break.

Question 12

Why can graphite be used as a lubricant?

Answer 12

Carbon atoms are arranged in layers, the forces between layers are weak intermolecular forces, this means they don’t need much energy to break, so layers slide over each other easily

Question 13

Does diamond or graphite have a higher melting point? Explain

Answer 13

Diamond has the higher melting point as it forms a continuous lattice where all atoms are held together by strong covalent bonds. In contrast, graphite includes weak intermolecular forces, which require much less energy to break