<span>To </span>calculate<span> the </span>atomic mass<span> of a single </span>atom<span> of an element, add up the </span>mass<span> of protons and neutrons. Example: </span>Find<span> the </span>atomic mass<span> of an isotope of carbon that has 7 neutrons. You can see from the periodic table that carbon has an </span>atomic<span> number of 6, which is its number of protons.</span>
