Science question- What's the difference between the following below?

Question

An atom of an element, an atom of a compound, a molecule of an element and a molecule of a compound. I know what a compound and an element is on its own- but what are these? How would you identify them if they were drawn? Thanks!

Answer 1

An atom of an element is clear, since an element is a substance made of one or more atoms of the same type.

A molecule of an element could be H₂, O₂, or even O₃.

A molecule of a compound would be a molecule of something which is not elemental, such as H₂O.

Answer 2

Atom of an element: One single unit of one type of atom on the periodic table (e.g. Mg, magnesium metal)

Atom of a compound: (no such thing, a compound is 2 or more pure elements mixed together, so there has to be at least 2 atoms present)

Molecule of an element: Two or more units of one type of atom (e.g. Cl2, chlorine gas as a diatomic molecule)

Molecule of a compound: 2 or more pure elements chemically combined together to form one unit (e.g. NaCl, sodium chloride - Na+ ion chemically bonded to Cl- ion in each 'unit' of the molecule)

On paper, these would look:

(X and O represent different elements, spaces in between means separate 'units')

Atoms of element: X  X  X  X  X

Molecules of element: OO  OO  OO  OO

Molecules of compound: XOX  XOX  XOX  XOX

Hope this helps!