Magic Numbers
Particular numbers of protons or neutrons that give a nucleus exceptional stability.
Formula / equation
2, 8, 20, 28, 50, 82, 126
Unit
Dimensionless
In depth
Magic numbers correspond to filled nuclear shells, the nuclear analogue of the noble gas electron configurations. Nuclides that are doubly magic, with both counts magic, are the most stable of all, and the shell model predicts an island of stability among superheavy elements.
Examples in the real world
Helium-4, oxygen-16, calcium-40 and lead-208 are all doubly magic and unusually abundant.