As such, chemistry departments are increasingly emphasising specialist
subjects. And we can now regard some key disciplines, such as biochemistry and
molecular biology, as the successful grown-up offspring of chemistry. The
Manchester chemistry graduate Michael Smith, for example, won a Nobel prize for
his contribution to gene technology.

The strength of chemistry lies in the breadth and diversity of its
applications, but perhaps its importance is overlooked because the most exciting
progress is now being made at the interface with other subjects. And more than
this, chemistry is creative. As I write, chemists are designing molecules that
exhibit all kinds of intriguing shapes, or that will assemble themselves into
fascinating and complex structures. What could be more creative than that?

As with all vital fields of endeavour, chemistry is changing. And as some
aspects mature, exciting topics develop. Among these are two different but
important growth areas. The first lucidly explained in Nicholas Terrett’s
Combinatorial Chemistry (Oxford, ÂŁ14.95, ISBN 0198502192), and the
second covered in Frank Jensen’s Introduction to Computational
Chemistry (Wiley, ÂŁ24.95, ISBN 0471984256).

Combinatorial chemistry is essentially jazzed-up synthetic chemistry.
Traditionally, a synthetic chemist will spend a lot of time and effort making a
single pure compound. Along the way, intermediates need to be isolated and
purified. This is all too slow for the pharmaceuticals industry, for example,
which demands rapid ways of testing large numbers of compounds as potential
drugs. So the new approach of combinatorial chemistry is to make a whole
“library” of molecules at the same time, using relatively few but efficient
steps.

I would have found the techniques a godsend when I started out as research
student. I wanted to make an oligopeptide that was like a soap molecule, with a
water-hating tail and a water-loving head. I tried to make it by solid-phase
peptide synthesis, a technique which won Bruce Merrifield a Nobel prize. But my
product was a hopeless mixture. I turned my attention to other things. Since
then, however, the technique has improved, so that not only can a particular
peptide be reliably constructed from its constituent amino acids, but reactions
can be carried out in parallel to give every possible combination of a
particular set of amino acids.

While some chemists devise ever more efficient ways of making molecules in
the lab, others prefer to work with virtual molecules. Computational chemists
use computers to answer questions that would be impossible or too time consuming
to answer in real life, such as what sorts of molecule are stable, and which
could never be made, how quickly can one molecule transform into anothe, and
what properties will a particular molecule have, and how do they change with
time.

As Jensen points out in his book, a newcomer in the field faces three main
problems. The first is understanding the language—an aspect Jensen
addresses by explaining the most important procedures and acronyms. The second
is running the programs. A textbook cannot help much with this, as the continual
development of hardware and software would quickly make it out of date. The
final problem is assessing whether the results are meaningful. Here, the
operator’s understanding, insight and experience come into play.

Chemistry is a challenging science, demanding a wide range of skills and
flexibility of approach. But it’s immensely rewarding. We can, in fact, be sure
it will go to the ball and live happily ever after.

Grass owes its greenness and blood its redness to molecules that belong to a
highly coloured family: the porphyrins from the Greek “porphura”, purple) and
porphyrin-like compounds. These molecules have complex structures, but at their
heart is a metal ion—magnesium in the case of green chlorophyll and iron
in the case of red haem—that is comfortably nestled between four linked
nitrogens.

Milgrom gives a clear explanation of the importance of these molecules to
life. Chlorophyll is responsible for trapping the energy of sunlight, so that
green plants can produce energy-rich carbohydrates and in the process generate
oxygen and maintain an atmosphere that enables all of us to live. Haem, neatly
wrapped up in a special protein, helps to transport oxygen around the body.

Even the debris from breaking down these molecules may be useful in nature.
Haem, for example, gives rise to bile pigments such as biliverdin, which is
green and colours the skin of many reptiles and amphibians, and the eggshells of
many birds.

Porphyrins are not only of interest for their roles in the natural world.
Chemists synthesise molecules like these for all kinds of reasons, and Milgrom
touches on ways in which they may be used in the future: in electronics and in
medicine, and for tapping alternative energy resources. This is a truly
fascinating class of molecules. While reading about them you can learn a lot
about chemistry and biochemistry.

There are many different porphyrins, but they represent just a tiny selection
of the vast number of compounds that organic chemists have been able to
synthesise. A student who perceives organic chemistry as a mass of factual
information to be memorised will soon either give up in despair—or go
mad.

What you need if you are to find your way through the organic chemistry maze
is an understanding of how and why reactions occur. And Adam Jacobs, in
Understanding Organic Reaction Mechanisms, brings this within your grasp by
presenting the principles that make sense of a complex subject. To understand
reactions you need to know about the bonds that hold molecules together, and to
understand bonding you need to know about the organisation of electrons in
molecular orbitals. This is where Jacobs begins.

Jacobs goes on to talk about the species that take part in reactions, the
types of reactions that can occur, and how to investigate their mechanisms. He
concludes with some case histories that illustrate the principles.

A more concise introduction to important mechanisms of organic reactions is
to be found in the Oxford Chemistry Primer No 45. You have to be
flexible when thinking about reaction mechanisms, always ready to update your
ideas in the light of new experimental evidence. Howard Maskill doesn’t just
describe mechanisms, he also indicates the type of evidence on which they are
based, and encourages his readers to weigh the evidence carefully.

Keeping track of all the evidence is getting easier now that computers are
increasingly being called upon as an aid to learning. The sixth edition of Peter
Atkins’ popular textbook Physical Chemistry includes a CD-ROM, while
the third edition of Mark Ladd’s Introduction to Physical Chemistry
promises that downloadable computer programs and solutions to problems will be
available on the Web.

This edition of Atkins is thinner and has larger pages than its predecessors,
presumably so that it appears less intimidating to students. It has all-new,
two-colour artwork and has been substantially rewritten.

Each chapter begins with a brief synopsis and ends with a checklist of key
ideas, suggestions for further reading and a selection of exercises and
problems, all designed to help the student get to grips with the subject matter.
The CD-ROM will run either on a Windows PC or a Macintosh, and is packed
with information, figures and animations.

One of the great advantages of Atkins over many of the similar textbooks that
originate from the US is the consistent and up-to-date use of nomenclature,
symbols and units. Ladd’s text is less comprehensive and less colourful than
Atkins’s, but goes into greater depth when discussing liquids and solids.

Many students, when first meeting physical chemistry, are thrown into panic
by the mathematical appearance of the subject. However, you’ll find a few key
skills—rearranging equations, keeping track of units and drawing
graphs—will take you a long way in the subject. Those who are worried by
such things are well advised to spend some time with the workbook Beginning
Calculations in Physical Chemistry by Barry Johnson and Stephen Scott. It
begins with very basic knowledge, explains how to set about solving problems,
and provides numerous exercises with answers.

For inorganic chemists there is a new edition of Chemistry of the
Elements by N. N. Greenwood and A. Earnshaw. It works through the periodic
table, describing the origins, properties and compounds of each element, with
many references to recent scientific literature. Interesting asides on such
things as ferroelectric crystals and the hydrogen economy are found in boxes
scattered throughout the text.

The more advanced student who is keen to read about recent developments in
the subject should turn to the new edition of Inorganic Materials by
Duncan Bruce and Dermot O’Hare. Nine chapters, each written by experts and most
of them updated from the earlier edition, cover topics ranging from
superconductors and molecular magnets to electronic materials. In a chapter on
metal-containing liquid crystals, we even meet up again with our old friends the
colourful porphyrins.

HOW many states of matter can you think of? Three come quickly to mind:
solid, liquid and gas. But consider water: the vapour normally behaves very
differently from the liquid, but the distinction between gas and liquid
disappears above a certain pressure and temperature. The message is that as we
try to understand more about the constituents of the world around us, we have to
refine the ways in which we think about them.

So we may think about matter in purely descriptive terms: a solid is hard, a
liquid can flow. Or we may have in mind a picture of what it is made of: the
molecules in a crystalline solid are ordered, in a liquid they are not. Or we
may go further and develop theories that enable us to describe atoms and
molecules, and the ways they interact, in mathematical terms. We are using
models—simplified representations of reality—to help us understand
the diverse nature of matter.

States of Matter, States of Mind by Allan Barton is about physics
and chemistry. Without an equation in sight, it deals with the conceptual models
we use to describe everything from the building blocks of an atom or the
behaviour of complex mixtures of molecules to the evolution of universes.

Although nonmathematical, the book is not trivial. Cartoons, sketches and
witty section headings may whet the reader’s appetite, but the text seeks to
express difficult concepts. It is not a substitute for a conventional
textbook—if you are to make real use of these ideas, you need to put
mathematical flesh on the conceptual skeleton. Nevertheless, it makes good
background reading for a keen student trying to get to grips with modern
physical chemistry, and it offers teachers new approaches to what they teach. It
is up-to-date, introducing recent concepts, new techniques and novel materials,
such as electrorheological fluids.

How many states of matter are there? Barton makes it clear that the
possibilities are endless. It all depends on how you perceive things.

Classics in Total Synthesis by K. C. Nicolaou and E. J. Sorensen, VCH,
Weinheim, Germany, ÂŁ32/$49.95, ISBN 3 527 29231 4

Organic Synthesis by Christine Willis and Martin Wills, Oxford
University Press, Oxford, ÂŁ4.99, ISBN 0 19 855791 4

Principles of Asymmetric Synthesis by Robert E. Gawley and Jeffrey
Aubé, Pergamon (Elsevier), Oxford,£48, ISBN 0 08 041875 9

Asymmetric Synthesis by Garry Procter, Oxford University Press,
ÂŁ19.50, ISBN 0 19 855725 6

Mass Spectrometry for Chemists and Biochemists (second edition), by
Robert A. W. Johnstone and Malcolm E. Rose, Cambridge University Press,
ÂŁ30/$39.95, ISBN 0 521 42497 6

Fundamental Toxicology for Chemists edited by John H. Duffus and
Howard G. Worth, Royal Society of Chemistry, ÂŁ29.50, ISBN 0 85404 529
5

FOR centuries, people have known that the yew tree contains a deadly poison.
In The Gallic War, written around 51 BC, Julius Caesar recounts how a
chieftain of the Eburones, Catuvolcus, committed suicide by taking yew extracts.
But something that is capable of killing may also bring healing. Taxol, a
powerful chemical extracted from the bark of the Pacific Yew, poisons cancer
cells. The problem is that a century-old tree may yield no more than enough for
a single dose.

This is where synthetic organic chemistry comes to the rescue. Chemists can
construct a molecule like taxol by “total synthesis”, building it from simple
starting materials. This is easier said than done with taxol, because the
molecule has a very complex structure. Each bond, each atom, must be in just the
right position. Chemists must think carefully about the molecule they want to
build, analysing it “retrosynthetically”. In other words, they have to consider
what reactions might give the final product, how those reactants might
themselves be prepared, and so on. New types of reaction may need to be
invented. Total synthesis is both art and science: it requires creativity and
skill.

The total synthesis of taxol is just one of 36 syntheses described in
Classics in Total Synthesis by Nicolaou and Sorensen. Strychnine,
penicillin V, progesterone and vitamin B₁₂ also appear among the
complex, biologically interesting molecules discussed in this book. In each
case, the authors outline the significance of the molecule, analyse it
retrosynthetically, discuss synthetic strategy and describe how it has been
prepared.

This will make a fascinating read for any student who wishes to follow in the
footsteps of chemists such as Robert Woodward and Elias Corey, both of whom
received Nobel prizes for their achievements in organic synthesis, and examples
of whose work feature in this volume.

A gentle introduction to the subject is offered by the Oxford Chemistry
Primer Organic Synthesis by Christine Willis and Martin Wills. The
principles of retrosynthetic analysis are presented, accompanied by stock
reactions that will create particular arrangements of chemical bonds. These are
followed by examples of syntheses.

Many organic molecules come in right-handed and left-handed forms.
Alternative forms of the same molecule—enantiomers—may behave quite
differently in biological systems. If a compound is to be used as a drug, one
form may be effective while the other is inactive, or even harmful. Chemical
reactions often yield a product consisting of a mixture of the two forms. It is
sometimes possible to separate the desired enantiomer from the mix, but then you
end up throwing away half the product. Of late, chemists have been keen to
develop synthetic methods capable of producing molecules selectively with a
particular handedness, an approach known as asymmetric synthesis.

Two recent books on the topic are suitable for advanced undergraduates and
research students. Principles of Asymmetric Synthesis by Robert
Gawley and Jeffrey Aubé discusses key physical concepts and analytical
methods and provides a useful glossary of terms, in addition to describing
important types of reaction. There are a great many references to recent
research. Asymmetric Synthesis by Garry Procter moves rapidly from a
brief discussion of principles to consider key classes of reaction.

A chemist must not only be familiar with methods of synthesis, but must also
have access to analytical tools to probe the structure of molecules. A mass
spectrometer is such a tool. In this instrument, a molecule is split into
charged fragments or ions, usually by bombarding it with electrons. The
fragments are then separated on the basis of their mass and charge. From the
resulting mass spectrum you can infer a likely structure for the original
molecule.

An up-to-date account of the technique appears in the second edition of
Mass Spectrometry for Chemists and Biochemists by Robert Johnstone and
Malcolm Rose. They add examples of the use of mass spectrometry for elucidating
structure, and they describe the different means of forming and separating ions.
These include recently developed methods for analysing proteins and other very
large molecules.

Johnstone and Rose also discuss how to combine mass spectrometry with various
forms of chromatography to analyse complex mixtures, and the ways in which
molecules may be modified to make them more amenable to analysis.

Many of the compounds we handle, whether in the laboratory or in the home,
are potentially harmful. The amount of legislation controlling hazard assessment
and the storage and use of chemicals has grown in recent years. Not only must
chemists follow certain procedures in their work, increasingly they must be
prepared to advise others on the safe handling of chemicals. With this in mind,
the International Union of Pure and Applied Chemistry has developed a text,
published by the Royal Society of Chemistry, Fundamental Toxicology for
Chemists, which aims to help chemists understand and minimise the risks
associated with the substances they use.

Toxicology is the science of poisons and as the physicist and alchemist
Paracelsus said in 1538, “What is it that is not a poison?” Even common salt,
essential to life in small amounts, has been used in parts of Asia as a suicide
agent. The effect of a substance depends on its dose, how it is taken in and
distributed through the body and how it interacts with particular organs within
the body. These and other factors are discussed in Fundamental Toxicology
for Chemists. There is a helpful glossary, and a suggested curriculum for
teaching toxicology in chemistry courses. Everyone handles poisons, so chemists
of all people should know how to handle them safely.

For others, “chemistry” equals “chemicals” equals “pollutants”. It is a modern evil, associated with smoking chimneys and dying fish, bad smells and poisonous substances. As far as they are concerned, chemistry has spawned an industry which has blighted our world and will destroy us.

Some are simply unclear about what chemistry is. In Britain, chemistry is frequently confused with pharmacy, and a chemist is assumed to be a person who dispenses drugs in a high street store. It has even been known for students to join a university chemistry course, only then to discover that it will not qualify them to handle prescriptions.

Even those who are proud to display on their coffee tables complicated books about space and time, and are keen to watch nature programmes, rarely idle away time with a chemistry text. When they turn to magazines like żěè¶ĚĘÓƵ, they learn a great deal about developments in biology, in computing and in astronomy, but remarkably little about chemistry. Chemistry’s offspring, such as biochemistry and molecular biology, fare much better than their parent.

Yet chemistry ought to be the most accessible of the sciences, for it deals most directly with all that surrounds us. It is about the composition of, and the changes that take place in, the material world. It concerns the air that we breathe, the food that we eat, the clothes that we wear, the tools that we use, and much more.

Chemical technology provides us with a great many of the things we take for granted in everyday life. The chemical industry makes a substantial contribution to the nation’s wealth. The chemist, far from being the person who contaminates our skies and streams, is likely to be the one who finds and analyses the problem, and seeks a solution.

Chemists must take some of the blame for the poor public understanding of their subject, for few are willing to put effort into explaining what it is all about. If the average person rarely reads a book about chemistry, it is partly because so few suitable books are available. If the typical bookshop offers so little on the subject for the general reader, one reason is that very few such books have been written.

It is, therefore, encouraging to see a new book by Peter Atkins, who lectures in physical chemistry at Oxford and is a fellow of Lincoln College. Well known for both introductory and specialised texts, he now brings us The Periodic Kingdom: A Journey into the Land of the Chemical Elements.

This is a book about the periodic table – the way in which the hundred odd elements can be organised to highlight the relationships between them. Since these elements combine to form all the diverse materials we find in the Universe, understanding their periodic pattern takes us to the very heart of chemistry.

Atkins perceives the table of the elements as an imaginary country, a kingdom in which each region represents an element. He introduces us to the geography of this land, guides us through its history and explains the laws that govern it, He acts as courier for those unfamiliar with the territory.

First, he takes us high above the kingdom, so that we can see all spread out below us, from the seeming aridity of the western metals, to the rich variety in the east. He points out the russet lake of bromine and another lake of shimmering, silvery mercury. We spot a brilliant yellow patch of sulphur. We spy multifarious carbon, here sooty black, there a twinkling diamond, then metallic, grey graphite and a trace of orange-brown fullerite.

Then we are given a closer look at some of the regions and learn of their products: iron, so important to humanity’s progress; sodium, which seethes and boils when rain falls on its territory, yet which in alliance with chlorine forms table salt; and calcium, the source of mortar and concrete, and so on.

When we focus on the ground in an area of the kingdom, we see that it has a texture like shingle. It is composed of pebbles and it is the nature of these pebbles – the atoms – that distinguishes one region from another. When we map the kingdom in terms of various properties of the pebbles, we begin to discern the periodic pattern that underlies the realm.

Our foray through the kingdom has revealed a rhythmic variation in the characters of the regions. If we are truly to understand this periodic pattern, we must investigate the structure of the pebbles themselves. We discover that they comprise a minute nucleus, itself composed of protons and neutrons, surrounded by a gossamer-like domain of electrons. It is the number of protons in the nucleus which distinguishes one region from another, but it is the electrons which are responsible for chemical action.

And it turns out that those electrons are associated with orbitals, no more than two per orbital, and that different types of orbital have different shapes and different names; there are spherical s orbitals, two-lobed p orbitals, four-lobed d orbitals and six-lobed f orbitals. The orbitals are arranged in shells around the nucleus, a bit like the layers of an onion, first a shell with just one s orbital, then a shell with an s and three p orbitals, then a shell with an s, three p and five d orbitals, and so it goes on. The point of all this becomes clear when we realise that the overall form of the periodic kingdom reflects the arrangement of electrons.

Having learnt about electrons and orbitals, we can also begin to comprehend the alliances – chemical bonds – that may occur within the periodic kingdom. We see how a metal from the west may willingly give up an electron to a nonmetal from the east, to form an ionic compound. We appreciate how two regions might share electrons to make molecules.

Our journey through the land of the elements has led us to discover some of the key concepts in chemistry. And on the way we meet some of the great explorers of this country and learn about the discovery of its various regions over many years, which continues today. Atkins tells us about the explorers, Joseph Priestley Humphry Davy, William Ramsay and the like, and he explains how the regions acquired their names. He takes us far back in time, to the very beginning of the Universe, and shows us how the whole kingdom developed from just one tiny island, hydrogen.

Then on to more recent history, as we are introduced to those who first sought to map the periodic kingdom: Johann Döbereiner, Beguyer de Chancourtois, John Newlands, William Odling, Lothar Meyer and Dmitri Mendeleev. The contribution of the Russian Mendeleev in 1869 was particularly significant because he was able to predict the existence and nature of regions that were yet to be discovered. Chemistry had come of age as a coherent, predictive science.

The periodic table of the elements adorns the walls of thousands of learned institutions; it has inspired and guided generations of chemists. This book provides a novel and fascinating approach to the topic, though at times the metaphor is stretched nearly to breaking point. You do not need much prior knowledge to travel with Atkins on this journey into the land of the chemical elements, but you do need to be ready to use both your imagination and your mind. If you are a newcomer to the periodic kingdom, gird your mental loins and venture forth with Atkins as your guide.