Carbon Allotropes

Diamond and graphite are both allotropes of carbon, which means that they are both only made of carbon.

Although they are made only of carbon, diamond and graphite are very different. They are only different because of the arrangement of the electrons.

Physical Similarities/Differences

In diamond, the atoms are very closely packed and each atom is connected to four other carbon atoms, giving it a very strong and rigid structure in three dimensions. This is what makes diamond very hard and almost unbreakable.

In the case of graphite, only the bonds between the graphite layers are weak, but the atom layers in graphite are very closely packed as well. The weak bonds between the layers is what makes graphite soft and slippery.

Chemical Similarities/Differences

In graphite, each carbon atom is covalently bonded to only three neighboring carbon atoms and these form layers of hexagonal network which are separated by a large distance. The fourth valence electrons remain free which enable an easy flow of electron through graphite and that is why it is made a good conductor of electricity. But this does not happen in case of diamond. In diamond, each carbon atom makes bonds with four other carbon atoms. So there is no free electron with carbon atoms to conduct electricity.

Diamonds cannot conduct electricity, but graphite can.

Uses

Graphite - Mixed with clay it is used in 'Lead' pencils. Since it is good conductor of electricity and is inert, it is used for making carbon electrodes in electrolytic cells and in dry cells. Because of its high melting point it is used for making graphite crucibles. Since it is soft and slippery, it is also used to make lubricant.

Diamond - Diamond membranes are durable, resistant to heat, and transparent, making them highly useful. Because diamonds are so hard and durable, they are ideal for grinding, cutting, drilling, and polishing. When used as an abrasive, very small pieces of diamond are embedded into grinding wheels, saw blades, or drill bits.

CITATION:

Diamond and Graphite. (n.d.). Retrieved December 27, 2016, from http://www.gemselect.com/other-info/diamond-graphite.php

BBC - GCSE Bitesize: Covalent bonding - giant covalent structures. (n.d.). Retrieved December 27, 2016, from http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/differentsubrev3.shtml

BBC - GCSE Bitesize: Graphite. (n.d.). Retrieved December 27, 2016, from http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/chemical_economics/nanochemistryrev2.shtml

USA: 1-585-535-1023UK: 44-208-133-5697AUS: 61-280-07-5697. (n.d.). Retrieved December 27, 2016, from http://www.chemistry-assignment.com/diamond-and-graphite

Element Encyclopedia

Carbon Allotropes