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 ...

In a scientific context, “pure” denotes a single type of material. Ostensibly, compounds contain more than one type of material. Yet both compounds and elements are considered pure substances. Pure ...

Different substances travel through a piece of chromatography paper at different speeds. Paper chromatography uses this to separate mixtures of soluble substances. It provides clues on the possible ...