Page 16 - Physical chemistry understanding our chemical world

Preface

This book

Some people make physical chemistry sound more confusing than it really is. One of
their best tricks is to define it inaccurately, saying it is ‘the physics of chemicals’. This
definition is sometimes quite good, since it suggests we look at a chemical system and
ascertain how it follows the laws of nature. This is true, but it suggests that chemistry
is merely a sub-branch of physics; and the notoriously mathematical nature of physics
impels us to avoid this otherwise useful way of looking at physical chemistry.
An alternative and more user-friendly definition tells us that physical chemistry
supplies ‘the laws of chemistry’, and is an addition to the making of chemicals. This
is a superior lens through which to view our topic because we avoid the bitter aftertaste
of pure physics, and start to look more closely at physical chemistry as an applied
science: we do not look at the topic merely for the sake of looking, but because
there are real-life situations requiring a scientific explanation. Nevertheless, most
practitioners adopting this approach are still overly mathematical in their treatments,
and can make it sound as though the science is fascinating in its own right, but will
sometimes condescend to suggest an application of the theory they so clearly relish.
But the definition we will employ here is altogether simpler,
and also broader: we merely ask ‘why does it happen?’ as we Now published as Rev-
focus on the behaviour of each chemical system. Every example elations of Divine Love,
we encounter in our everyday walk can be whittled down into by Mother Julian of
small segments of thought, each so simple that a small child can Norwich.
understand. As a famous mystic of the 14th century once said, ‘I
saw a small hazelnut and I marvelled that everything that exists could be contained
within it’. And in a sense she was right: a hazelnut looks brown because of the way
light interacts with its outer shell – the topic of spectroscopy (Chapter 9); the hazelnut
is hard and solid – the topic of bonding theory (Chapter 2) and phase equilibria
(Chapter 5); and the nut is good to eat – we say it is readily metabolized, so we think