The person above me’s answer is unfortunately wrong. since atoms are made of electrons, protons, and neutrons, they can obviously still be broken down. the correct answer is elements.
Mass number<span> is the </span>number<span> of protons </span>and<span> neutrons in an atom. </span>Atomic mass<span> is the average </span>mass<span> of all the isotopes of a certain type.</span>
