Diamond and Graphite

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					                      Diamond and Graphite

The element carbon can exist in either of two forms: graphite or diamond

Graphite

We see the most common form of carbon in coal, charcoal and soot. These
are forms of graphite which are bonded together by impurities in
different ways. Graphite is made up of sheets or layers of covalently
bonded carbon atoms arranged in hexagons. However, the bonding
between the layers is very weak, allowing them to slip over one another,
giving graphite its excellent lubricating characteristic.

Diamond

Diamond is a very hard crystalline material. Each carbon atom is strongly
covalently bonded to four other carbon atoms, in a pyramid arrangement.
This extends to form a giant covalent structure.

Graphite and diamond are called allotropes, because they are made up of
the same element – carbon – and exist in the same physical state.


                     Strong COVALENT bonds




                             Weak bonds




               Diamond                                Graphite




Why is graphite a good conductor of electricity and diamond is
not?
Summarizing the similarities of and differences between the   Summarizing the similarities of and differences between the
two allotropes:                                               two allotropes:

Both diamond and graphite                                     Both diamond and graphite

   (1) Are made ONLY of carbon atoms                             (5) Are made ONLY of carbon atoms
   (2) Have high melting and boiling points                      (6) Have high melting and boiling points
   (3) Contain “Covalent” bonds                                  (7) Contain “Covalent” bonds
   (4) Are “Giant” molecules                                     (8) Are “Giant” molecules



      But they differ in several ways:                              But they differ in several ways:

   Write down what you think the differences would be, eg,       Write down what you think the differences would be, eg,
   structure, expense, etc, between diamond and graphite.        structure, expense, etc, between diamond and graphite.


           Diamond                            Graphite                   Diamond                            Graphite

				
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posted:7/5/2011
language:English
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