Compounds are made up of two or more elements.
Magnesium is a chemical element, not a compound.
Copper is a chemical element. It can be a compound but copper is usually known as a chemical element.
Pb is a compound.
Radium is a chemical element; a compound has a minimum of two chemical elements.
Sodium is a chemical element. Salt is a compound of sodium and chlorine.
Helium (He) is a chemical element, not a compound; the chemical symbol is He.
Neon (Ne) is a chemical element, not a compound.
Francium is not a compound, but a chemical element.
Americium is not a compound, it is a chemical element.
A metal is a chemical element not a compound.
We have chemical symbols so that we can quickly write about an element or compound with out having to write out the name every time you want to refer to it.
If something is not a mixture then it is a pure substance, either an element or a compound.