ABSTRACT
Matter is defined as that which occupies space (see 18.1). Our discussion of the composition of matter begins with the chemical elements. The term ‘element’ is used for substances which cannot be further divided by chemical means. All the matter in the universe is made up of chemical elements. There are 92 naturally occurring elements and a further 20 or so have been produced in the laboratory. Many elements – carbon, calcium, sulphur and lead, for example – have names that are in everyday use, but others are rare and their names much less familiar.
