Atom
The smallest particle of an element.
A single atom of oxygen (O).
Element
A substance made of only one type of atom.
Everythting found on the periodic table
Oxygen (O₂), Gold (Au), Carbon (C).
Mixture
2 or more elements chemically not bonded together
Compound
2 or more elements chemically bonded together
e.g Water (H₂O) → made from hydrogen and oxygen.
molecule
A molecule is made when two or more atoms are chemically bonded together.