Describe the difference between the terms "element", "compound", "molecule", and "salt".

You can define an element as a substance with only one type of atom in (e. g. only sulphur atoms). If a substance has more than one type of atom in, then it is either a compound or a mixture, depending on whether the elements have bonded. Examples of elements are:

Oxygen

Sulphur

Carbon

Hydrogen

Protactinium

Compound-

A substance made up of atoms of two or more different elements joined by chemical bounds.

Molecule - a pure substance that cannot be broken down

Salt - A Ionic Compound Formed From The Reaction Of An Acid And Base.