Unit 2.6 - giant covalent structures

Question 1

What type of structure does diamond have?

Answer 1

Giant covalent in a 3D tetrahedral arrangement. Each C atom is covanlently bonded with 4 other c atoms.

Question 2

Why is diamond so hard?

Answer 2

It is made up of many strong covalent bonds in a giant structure.

Question 3

State the main use of diamond

Answer 3

In cutting tools and drill bits (because it is the hardest material in the world)

Question 4

State 4 properties of diamond

Answer 4

1. Extremely high mp - strong covalent bonds require a lot of energy to break
2. Extremely hard
3. Electrical insulator - no mobile charged particles that can form an electric current
4. Thermal conductor

Question 5

Explain graphite’s structure

Answer 5

Each carbon atom in graphite is only bonded with 3 other c atoms in a 2D hexagonal layered arrangement.
The 4th electron is delocalised (able to move freely through structure) and is not involved in bonding)

Question 6

Properties of graphite

Answer 6

1. Extremely high mp - strong covalent bonds
2. Flaky & brittle - layers of carbon atoms can easily slide off each other because the
   intermolecular forces between them are weak
3. Electrically conductive - delocalised electrons form an electric current

Question 7

State 3 uses of graphite

Answer 7

1. Lubricant between machine parts
2. Electrodes in electrical cell
3. Pencils/crayons

Question 8

State the properties of giant covalent structures

Answer 8

1. Low volatility (high mp)
2. Insoluble in water
3. Do not conduct electricity (except graphite)

Question 9

Explain giant covalent structure

Answer 9

Huge numbers of atoms held together by covalent bonds

Question 10

What is the difference between simply covalent and giant covalent structures?

Answer 10

They both have the same type of bonding but simple covalent molecules have a small and fixed number of atoms, while giant structures have large and variable numbers of atoms.