Magic numbers

Definition

Magic numbers are specific numbers of nucleons (either protons or neutrons) that result in a more stable nucleus due to closed nuclear shells. These numbers correspond to completely filled energy levels within the nucleus.

5 Must Know Facts For Your Next Test

1. The most commonly recognized magic numbers are 2, 8, 20, 28, 50, 82, and 126.
2. Nuclei with magic numbers of both protons and neutrons are called doubly magic and exhibit extraordinary stability.
3. Magic numbers arise from the shell model of the nucleus, which is analogous to electron shell structures in atoms.
4. Isotopes with magic numbers tend to have higher binding energy per nucleon compared to neighboring isotopes.
5. The concept of magic numbers helps explain why certain elements are more abundant in nature.

Review Questions

• What is the significance of a nucleus having a 'magic number' of nucleons?
• List at least three commonly recognized magic numbers for nucleons.
• How do magic numbers contribute to the stability of a nucleus?

Related terms

Nuclear Shell Model:

A model of the atomic nucleus which proposes that nucleons move in quantized orbitals, similar to electrons in atoms.

Binding Energy:

The energy required to disassemble a nucleus into its component protons and neutrons. Higher binding energy indicates greater stability.

Isotopes:

Variants of a particular chemical element which differ in neutron number but have the same number of protons.