What mostly contains the atoms of two or more types of elements. The number of atoms can range from two to many thousands

The answer is Molecule.

Explanation:

A molecule is an electrically neutral and stable group of at least two atoms in a defined configuration, joined by strong chemical bonds (covalent or ionic bond).

A molecule can consist of several atoms of a single chemical element, as in the case of diatomic oxygen (O₂), or of different elements, as in the case of water (H₂O).

The macromolecules or polymers are constituted by the repetition of a unit and that reach relatively high molecular weights.