Giant Covalent Molecules

• Science
• Upper Secondary (Key Stage 4)
• GCSE

Draw the electron structure of Carbon

What terms means a chemical that contains 2 or more elements chemically bonded to each other?

electron shared by H

electron shared by O

electrons not being shared by O

What terms means a chemical that contains 2 or more elements chemically bonded to each other?

Write down the number of atoms of each element in methane

What is a covalent bond?

Diamond

• Each C is bonded with 4 other C atoms
  
• It has a very rigid structure
  
• It has a very high MP and BP as all C atoms are covalently bonded together and it takes a lot of energy to over come these bonds
  

It does not conduct electricity as there are no free electrons

Each C forms only 3 covalent bonds
How do you think this affects the properties of graphite compared to diamond?

Graphite

• Each C forms only 3 covalent bonds
  
• Graphite exists in sheets of C atoms arranged in hexagons
  
• The C atoms are held together by covalent bonds, so graphite has a high melting point
• The layers in graphite are held together by weak intermolecular forces which means that these forces can break easily
  
• This means that graphite is soft and slippery and allows pencil marks to be made on paper!

Graphite

• Each C forms only 3 covalent bonds
  
• Graphite exists in sheets of C atoms arranged in hexagons
  
• The C atoms are held together by covalent bonds, so graphite has a high melting point
• The layers in graphite are held together by weak intermolecular forces which means that these forces can break easily
  
• This means that graphite is soft and slippery and allows pencil marks to be made on paper!

Why does graphite conduct electricity?

	Graphite	Diamond
Number of covalent bonds
Strength
Conducts electricity
Melting point

four

three

strong

soft

Yes

No

Very high

Very high

Describe this structure.

Graphene

Graphene is a single sheet of C atoms joined together by covalent bonds

They are joined together in hexagons

It is a single layer of graphite, and the sheet is one atom thick

Graphene is strong because of the covalent bonds

It is also very light

It can conduct electricity as it has delocalised electrons

What is best description of a fullerene molecule?

1. Molecules shaped like balls or tubes
2. Hollow molecules
3. Hollow molecules in the shape of balls
4. Hollow molecules in the shape of balls or tubes

In fullerene molecules the carbon atoms are arranged as...

1. hexagons
2. squares
3. octagons
4. circles

How many carbon atoms are there in a Buckminster Fullerene?

1. 20
2. 40
3. 60
4. 80

Give the name of the molecule shown.

1. Tubes
2. Nanotubes
3. Buckminster Fullerene
4. Graphite

Nanotubes can conduct

1. electricity only
2. heat only
3. electricity and heat
4. nothing

Give three uses of fullerenes