EPSC201 - Lecture 11 Notes
Minerals are naturally occurring, chemically pure solids. Crystals are made up of minerals. Halite
is a mineral that forms a cubic structure crystal. Halite is also common table salt, NaCl. The
bonds that link the sodium and chlorine are ionic bonds, which means there was an electron
The electron transfer causes the atoms to form charged substances called ions.
Cation = positive ion (Na+)
Anion = Negative ion (Cl-)
The outer shell of both atoms want to have 8
electrons. Neutral sodium atoms have 9 elec-
trons in the outer shell, so sodium gives off a
electron, losing a negative charge. This makes
sodium have a net 1 positive charge. The chlo-
rine gains the one electron, giving it 8 total, and
a net -1 charge.
Atoms vary in size. The variation in size causes crystals to pack in different ways. Cations and
anions want to be next to each other, and repulsed by like ions. Opposites attract, likes repulse.
The shape of the crystal is determined by the size of the atoms packing around each other, called
Diamonds are a very hard substance. They can
scratch any other material. Diamonds can scratch
glass, while copper and iron won’t be able to.
They are softer then diamonds. There are no sub-
stances on earth that are harder then diamonds.
Diamonds don’t scratch, but they can shatter. If
you hit a diamond with a hammer, it will shatter
into dust. In diamonds, carbon atoms are bonding to other carbon atoms. The atoms are sharing elec-
trons. All the atoms have the same elctronic configuration. This is refered to as a cavalent
bond. (Sharing electrons between atoms)
The Big Hole at Kimberly, South Africa, was the
first mine to find diamonds. Diamonds come from
deep inside the earth. They form at very high
pressures, and high temperatures. These condi-
tions are found at 250 km deep. Carbon at shal-
lower depths forms graphite. Both diamonds and
graphite are pure carbon. Even around 100 km
there are diamonds forming.
Diamonds are the stable form of carbon at big
depths. Graphite is the stable form at shallower
depths. Liquid formed at depths move upwards towards the surface. As it moves upwards it
plucks off pieces of mantle. Magma helps the mantle move upwards toward the surface. Frag-
ments of the solid mantle are brought to the surface by magma, which sometimes contain dia-
Kimberlite – fragments of mantle containing diamonds
Magma – molten rock below the earths surface
Discovery of diamonds in South Africa was made by a 10 year old kid. They were playing mar-
bles. In Hope Town, there was a doctor who recognized these marbles as diamonds. This
caused a mining rush for diamonds. Mining claims were two meters by two meters, which was
Seccil John Rhodes – bought all these small claims, and made himself a millionaire. This created
the mining industry in S.A.
There has been a recent discovery of diamonds in Quebec.
There is speculation that there is a planet dominated by carbon. It is about twice the size of
earth. The theory is that it is rich in diamonds below the surface.
In graphite, the atoms are arranged in a series of planes. The planes contain the same bonds as
diamonds, carbon carbon bonds, but only in the plane. A pencil is able to lay down sheet of
graphite, because it breaks easily in one direction, along the plane.
The planes are held together by Van der Waals forces. Impregnating other materials with
graphite allow the material to slide, because the planes slide along each other. This makes the
material, found in tennis rackets for example, flexible. Diamonds do not last forever, as suggested by advertising. However, the kinetics along the dia-
monds to be stable for around billions of years. So they will be safe in normal conditions for a
If a diamond were put in the oven, with oxygen present, it will combust.
Carbon + oxygen = carbon dioxide
This is the combustion formula. This occurs when you burn wood. If a diamond is heated hot
enough, it will combust and form carbon dioxide.
Water molecules like to form weak bonds with each other, called Hydrogen Bonds. The water
molecule is polar, because the oxygen is extremely electronegative, and the hydrogen is elec-
tropositive. The net result is the molecule behaves as a bar magnet