The law of conservation of mass is not known as "atoms". The law of conservation of mass states that in a closed system, the total mass of the reactants before a chemical reaction must equal the total mass of the products after the reaction.

Here's why the law of conservation of mass is related to atoms:

* Atoms are the building blocks of matter: All matter is made up of tiny particles called atoms.

* Atoms are not created or destroyed in chemical reactions: In chemical reactions, atoms are simply rearranged, not created or destroyed.

* Mass is a property of atoms: Each atom has a specific mass.

* Total mass remains constant: Because the number and type of atoms remain the same in a chemical reaction, the total mass of the system must also remain constant.

Therefore, the law of conservation of mass is a consequence of the fundamental nature of atoms. The law itself doesn't define atoms, but it is a direct result of the fact that atoms are the fundamental units of matter and are conserved in chemical reactions.