Compare: The mass number of C-12 is 12, a value representing the total number of protons and neutrons in the nucleus. Since both protons and neutrons have masses that are just over 1 u, the mass number will typically be very close to the atom’s mass. Add a few atoms each of C-12 and C-13 to the chamber, press Release atoms, and then click on the bars of the graph to reveal a close-up image of each isotope. 1. How does the proton number in each isotope compare?
2. How does the neutron number in each compare?
3. What can you conclude about the role of neutrons in forming new isotopes?