Skip to main content
Glite Dictionary
magic number

magic number

1 9.2
A number of protons or neutrons that makes a nucleus especially stable
  • noun
  • /ˈmædʒɪk ˈnʌmbər/
  • Specialized
translation icon : número mágico
  • The element exhibits remarkable properties when its nucleus contains a magic number of 50 protons.
  • magic number 20

A nucleus, which has a magic number of both neutrons and protons is called doubly magic.

Examples

  • The atomic nucleus is particularly stable when it has a magic number of 20 nucleons.

  • A nucleus, which has a magic number of both neutrons and protons is called doubly magic.

    Sabine Hossenfelder

  • By attempting to solve only the synchronization problem, they also removed degeneracy and, incidentally, obtained the magic number 20.

    Academic text (1996)

  • Their only experimental criterion for judging success was the "magic number," 20, of amino acid residues that occurred naturally in proteins and, therefore, must be coded for by DNA.

    Academic text (1996)

  • The celebrated triumphs of the shell models in explaining properties such as the special stability of nuclei with certain "magic numbers" of neutrons and protons have generally involved nuclei that are spherical, or very nearly so.

    Academic text (1995)

  • In nuclear physics, isotopes with a magic number of 8 are known for their enhanced stability.

Surface Forms

magic number singular
magic numbers plural

Morphology

magic + number

A B1 learner who knows 'magic' and 'number' would likely infer 'a special or notable number' because 'magic' metaphorically signals something exceptional; however the specific technical sense referring to particular nucleon counts and nuclear stability is specialized and cannot be derived from the parts alone. The expression is therefore partially predictable (metaphorical transparency) but requires domain knowledge for the full meaning.

Etymology

Magic number comes from scientists who noticed that certain numbers of particles in the center of an atom made that center very stable; they called that number 'magic' because it seemed to give a surprising, almost 'magical' stability. So, magic number now means a number of protons or neutrons that makes the center of an atom especially stable.