Allotropes of carbons

What are allotropes?

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

What are some common allotropes of carbon?

Carbon, graphite, fullerenes

How many bonds does the carbon atoms in diamond form?

Each atom forms four covalent bonds - makes diamond really hard

Why does diamond have a high melting point?

Large amounts of energy are needed to overcome their strong covalent bonds

Why does diamond not conduct electricity?

It has no delocalised electrons or ions

How many bonds does the carbon atoms in graphite form?

Each atom forms three covalent bonds - creates sheets of carbon atoms arranged in hexagons

How are the layers between graphite held together?

There are no covalent bonds between layers - they're only held together weakly, so they're free to move over each other

What makes graphite soft and slippery?

The layers are free to slide over each other because there are no covalent bonds between the layers

Why is graphite ideal as a lubricating material?

It's soft and slippery

Why has graphite got a high melting point?

The covalent bonds in the layers need loads of energy to break

Does graphite conduct electricity?

Yes it also conducts thermal energy, as only three out of each carbon's four outer electrons are used in bonds, so each carbon atom has one delocalised electron that can move freely throughout.

What is graphene?

A single layer of graphite

What shape is graphene joined together in?

Hexagons

How thick is graphene?

One atom thick, making it a two dimensional substance

Why can graphene be added to composite materials?

The network of covalent bonds makes it very strong, it's also incredibly light ----> added to composite materials = improving their strength without adding much weight

Can graphene conduct electricity?

Yes because it has delocalised electrons = has the potential to be used in electronics

What are fullerenes?

Molecules of carbon atoms shaped like closed tubes or hollow shapes

What are fullerenes made up of?

Mainly carbon atoms arranged in hexagons can also contain pentagons or heptagons

What are fullerenes used for?

To 'cage' other molecules by forming its structure around another atom or molecule, which is then trapped inside.

Used to deliver drugs into the body

Why do fullerenes have a huge surface area?

They could help make great industrial catalysts - individual catalyst molecules could be attached to the fullerenes

Are fullerenes lubricating?

Yes

What can fullerenes form?

Nanotubes - tiny carbon cylinders

What are properties of nanotubes?

-Conducts electricity and thermal energy

• Ratio between the length and the diameter of the nanotubes is very high

• A high tensile strength (don't break when stretched)