table may have the same structure as the modern
equivalent, but it contained only 88 elements,
it finished at element 92, and had 4 gaps. Since
then we have discovered many more elements. It
is believed that we now know all of the elements
that occur naturally on our planet, but it is
possible that there are still many undiscovered
elements, perhaps elements that are not normally
found on Earth. Bombarding atoms with high energy
particles in order to literally metamorphose one
element into another is also possible. Particle
accelerators speed up the particles within an
atom until they collide, creating enough energy
to produce new elements. Sometimes only minor
quantities of these new elements have been made.
For instance, scientists who made element 109
produced only one atom, and within milliseconds
it had decayed.
Currently, we do not know the atomic weight of
elements 110 and 111 since they were only produced
once: scientists have not yet managed to make
them again. Element 114 was discovered in 1999,
but is only existed for a mere 30 seconds! Elements
116 and 118 were discovered in 1999, but again,
they were only in existence for less than a millisecond,
since they decay very rapidly.
Our ability to discover new elements may be limited
to the technology that we currently possess.
For more information about the elements, visit
Chemsoc, the Royal Society of Chemistry’s
chemical science network (www.chemsoc.org)
Living things are largely composed of water and
all the chemical reactions in our bodies, metabolism,
take place in solution in water, so it is an essential
component of all living things. Living things
also contain carbohydrate, fat, protein, vitamins,
nucleic acids and minerals. With the exception
of the minerals, these are organic carbon-based
substances. Our flesh is mainly protein and this
contains carbon, hydrogen, oxygen, nitrogen and
a little sulphur. The reactions in our bodies
only go fast enough because they are catalysed
by enzymes and these too are protein molecules.
The energy required for movement, growth, repair
and to keep us warm comes from carbohydrates.
These chemicals contain carbon, hydrogen and oxygen
as does fat. Our DNA is yet another carbon-containing
chemical. The one common feature of these chemicals
is that they all have a carbon chain to which
various other atoms are bonded. All life on Earth
is carbon based. Organic chemistry is the study
of compounds of carbon including many chemicals
not found in living things.
Biologists have noted the proximity of carbon
and silicon in the periodic table. Both elements
are in Group 4 of the periodic table. NB Modern
chemists now refer to these elements as Group
14. Elements in the same Group of the periodic
table have very similar properties. In fact our
cells have difficulty in distinguishing between
calcium and strontium, both in Group 2 of the
periodic table. Some scientists have supposed
that it might be possible for some kind of life
form to develop using silicon instead of carbon
as the basis for life. Such organisms might have
evolved on other planets in remote solar systems
under very different conditions or even in the
fiercely hot magma beneath the Earth’s crust.
The possibility of silicon-based life forms is
fascinating. But although the chemistry of silicon
is similar to that of carbon, there are significant
differences. Metabolism, the chemical reactions
in living things, can be divided into two kinds
of reactions. Anabolic reactions take simple chemicals
and build more complex ones from them using an
energy source. Chemosysnthesis, photosynthesis,
growth and repair are all anabolic processes.
The idea of silicon-based life supposes that there
is a simple silicon compound and suitable solvent
that could be chemically combined into more complex
chemicals. Digestion, decay and respiration are
all catabolic processes. Complex chemicals are
broken into simpler ones releasing energy required
for other purposes. The idea of silicon-based
life supposes that there are complex silicon chain
macromolecules that could serve the functions
of carbohydrates, fats, proteins, vitamins and
Silicon dioxide is a solid. However it is very
abundant on Earth: sand! Perhaps on another planet
there might be a suitable gaseous or liquid silicon
substance. This might be silicon dioxide at much
higher temperatures and pressures than here on
Earth. It might be silicon nitride, silicon hydride,
silicon chloride or some other covalent compound.
The first essential requirement for a silicon-based
life form is the possibility of converting a simple
silicon compound into a more complex and stable
one using an energy source, heat, electricity,
light, sound? The second essential requirement
for silicon-based life is the existence of complex
silicon compounds that can serve as energy sources,
catalysts for silicon metabolism and control or
information substances. The third essential requirement
for silicon-based metabolism is the existence
of a suitable solvent. This need not be water.
There are over 100 different elements and therefore
millions of possible combinations of them. The
possibility of silicon-based life is an interesting
research topic. It is worth noting that a silicon-based
microbe would be unable to utilise our cells as
an energy source, though a silicon-based alien
lifeform could exist.
for more information about silicon.
Did you know that there are
over 100,000 new
molecules being made every year? These molecules
are new materials that could save lives in the
In order to discover new drugs, and to improve the
drugs that are currently available, chemists have
to find out which molecules are most effective.
To do this, they use combinatorial chemistry. This
is a relatively new technology that allows the manufacture
of thousands of different molecules, which can be
tested at the same time. Only 15 years ago, chemists
could only test one molecule at a time, to see if
they affected biological activity that could help
fight disease. This form of testing was quite long-winded
and progressed to using polymer beads in order to
test new materials. Nowadays, tests are done on
silicon chips – and chemists can test over
100,000 different ratios of reactants per day, and
in very tiny amounts. This means that scientists
can assess reactions to identify promising molecules.
The most promising molecules can. It is even possible
to create ‘virtual’ molecules on the
computer and test them by modelling their actions
in the body, before they are even made. This is
how new pharmaceuticals are made: scientists use
the traditional scatter-shot technique of creating
molecules, but in a smart way.
To find out more about new drugs,
go to the British
Whether a substance is liquid,
gas or solid should be easy to identify, shouldn't
it? You would've thought so, but did you know
that there are actually 'in between states', that
there are more states than just liquid, gas and
solid? A substance can look like a solid but may
actually be more liquid than solid!
Take elastic, for example. This
is more liquid than solid since it behaves in
way that defies the usual definitions of a 'solid'.
Liquid crystal is another example of a substance
that does not fit into the usual definition of
And what is plasma, then? Is
it a liquid, or is it a solid? Plasma is actually
a fluid made up of electrically charged particles.
Some or all of the electrons are stripped off
the atoms, leaving positively charged ions and
electrons. Its properties are very specific because
of this electrical charge, making it behave very
differently from other states of matter, hence
plasma is often referred to as the 4th
state of matter. Plasma is formed when
atoms are broken up into parts, as opposed to
combining with other atoms to form complex structures
as with solids, liquids and gases. This plasma
state of matter is of great importance to our
future energy source: it plays a key part in nuclear
For more information about the states of matter,
go to Chemtutor.com
The first sub-atomic
particle to be discovered was the electron,
in 1870s by a scientist called J.J. Thomson, with
Rutherford discovering the proton in 1919, and
in 1932, James Chadwick discovered the neutron.
It was thought that protons, neutrons and electrons
were the smallest particle in existence. But then,
it was discovered that many fundamental particles
exist. In 1964, a physicist called Murray Gell-Mann
found that there were 200 sub-atomic particles
that could be reduced to 'fundamental'
particles called quarks: and
that there are actually different types of quarks,
and they combine in different ways. The first
5 quarks have been named 'up', 'down',
'strange', 'charm', and 'bottom'.
A 6th quark, called 'top', was discovered
only in 1995!
There is a theory that quarks are the key to
the beginning of all things; that a kind of quark-electron
soup led to the formation of hydrogen, helium
and lithium nuclei.
It is widely thought that quarks are the smallest
particle that exists. The future of sub-atomic
discovery could remain with our present theory
that quarks are the smallest particles that exist,
but there are more 'theoretical' particles:
for example, Gluons are hypothetical
sub-atomic particles that are thought to play
a part in the way quarks interact, by channelling
the attractive force between each quark particle.
It is thought that the 6 quark types are held
together by gluons - there are currently thought
to be 8 different kinds of gluon. This field of
chemistry is called quantum chromodynamics.
To find out more about sub-atomic particles,
go to The