Example Question #1 : The Periodic Table
On the periodic table, carbon is atomic number and has an atomic mass of . How many sub-atomic particles are found in the nucleus of a carbon atom?
The standard sub-atomic particles are protons, neutrons, and electrons. Protons and neutrons are found in the nucleus, while electrons move freely around the nucleus. This question is specifically asking about the number of protons and neutrons in an atom of carbon.
Each proton and each neutron has a mass of approximately . Since the atomic mass of a carbon atom is , we can conclude that there are twelve sub-atomic particles in the nucleus (twelve total protons and neutrons).
The atomic number refers to the number of protons in the nucleus of the atom. Since the atomic number of carbon is six, there are six protons in the nucleus. For this question, however, we need the total of both the protons and neutrons (not just the protons).