The Nuclear Periodic Table (IMAGE) Kyoto University Caption Protons have different stable magic numbers: 2, 8, 20, 28, and so on. When nuclear orbits are filled with protons, they form stable nuclei, analogous to the noble-gas elements Credit Kyoto University/Yoshiteru Maeno/Kouichi Hagino Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.