Introduction
History
The 4C
Properties
Buy a diamond
Tips For Diamonds
Forever
Diamond Facts
Types of cutting
FAQs
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Diamonds Forever
Blood is thicker than water, and other types of bonding,
such as covalent bonding, are stronger than ionic bonding. After all, if you
drop some ionically bonded salt into water you just end up with salty water:
the positive and negative charges on the sodium and choride atoms are
surrounded by water molecules which break the ionic bonding. Drop a diamond
into water, and it remains a diamond, because it has covalent bonding
between its carbon atoms. (But diamond is not "forever", and like other
forms of carbon can be burned in a very hot fire !).
The covalent bonding in diamond consists of electrons that are intimately
shared between the carbon atoms. We already saw that these strong covalent
bonds are usually represented by drawing them as sticks between the atoms.
Diamond is important because it is the hardest substance known, and can be
used for making sharp cutting tools, such as used in drilling for oil. Other
important materials, such as silicon and germanium used for computer chips
also have the diamond structure.
There is a common alternative to diamond for the structure of carbon -
graphite. The carbon atoms in graphite are also strongly joined by covalent
bonds, but only within a plane, unlike the 3D network of bonds in diamond.
These planes of carbon atoms simply stack together one on top of the other,
with only very weak forces between them. The planes of carbon atoms can then
easily slip over each other, and graphite is therefore an important
lubricant ! Talcum powder feels smooth for similar reasons.
Drawn like this, diamond and graphite look very different, and of course so
they are. But if we look down the cube body-diagonal direction of diamond,
which is perpendicular to the planes of packing, we see the trigonal
symmetry, which gives a somewhat different picture.
Now if we look down the corresponding direction for graphite, which is again
perpendicular to the planes of packing, we see the hexagonal symmetry, and
some similarity between the structures of these two very different
materials.
Recently a large number of new carbon structures with exciting properties
were discovered. The famous buckyballs consist of 60 carbon atoms bonded
together to form a hollow sphere. These C60 structures look like tiny
geodisic domes of the type made famous by the architect Buckminster-Fuller
(hence the common name buckyball).
Larger spheres and ellipsoids can also be constructed, and even hollow
nanotubes of carbon, as if graphite layers were rolled up to form
microscopic pipes. These new materials, called Fullerenes, have exciting
physical and chemical properties that are only now being explored
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