Everything we can see and touch, and quite a lot that we can’t as well, is made of tiny particles called atoms. Some substances, like particles of this iron, contain only one kind of atom. Iron is an ...

During the past 25 years, chemistry professor James L. Marshall of the University of North Texas, Denton, has collected pure samples of nearly all the elements from hydrogen through uranium. In ...

In everyday life, for example on food packaging, the word ‘pure’ usually means that something is in its natural state without anything added to it, like sweeteners or preservatives. Natural fruit ...