A collection of atoms is called a molecule if the atoms are bonded together.

If the atoms are not bonded, it is simply a collection of atoms.

Here's a breakdown:

* Molecule: Two or more atoms held together by chemical bonds. Examples: Water (H₂O), Carbon dioxide (CO₂), Oxygen (O₂)

* Collection of atoms: A group of atoms that are not chemically bonded. Examples: A sample of pure gold, a mixture of gases.

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