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 .