Definition

Noun: 1. A specific number of protons or neutrons in an atomic nucleus that confers exceptional stability: In nuclear physics, a "magic number" refers to one of several integers (2, 8, 20, 28, 50, 82, and 126) representing a count of nucleons (protons or neutrons) that completely fill nuclear shells. Nuclei with these numbers are significantly more stable and tightly bound than others. 2. A significant or crucial number in a specific context: In broader, non-scientific usage, a "magic number" can refer to any number that is critically important for achieving a desired outcome within a particular system, process, or game.

Usage Examples

• Scientific Context:
  • Oxygen-16 is considered "doubly magic" because it has 8 protons and 8 neutrons, both of which are magic numbers.
  • The stability of lead-208 is attributed to its 82 protons and 126 neutrons, which are both magic numbers.
• General/Figurative Context:
  • In baseball, a team's magic number is the combined number of their wins and their rival's losses needed to clinch a playoff spot.
  • For this software, 1024 is the magic number for optimal buffer size.

Advanced Usage

• "Doubly magic" nucleus: A nucleus where both the proton count and the neutron count are magic numbers, leading to extreme stability.
  • Helium-4, with 2 protons and 2 neutrons, is the lightest doubly magic nucleus.

Variants and Related Words

• Magic (adj): Possessing or using supernatural powers; wonderful, excellent. (e.g., , ).
• Number (n): An arithmetical value; a quantity or count.

Synonyms

• Scientific: Shell closure number, stable nucleon count.
• General: Key number, critical number, target number.

Related Phrases

• To hit the magic number: To reach the crucial or target figure.
  • The sales team finally hit the magic number for their quarterly goal.

Related Idioms

• The magic number is...: A phrase used to introduce or emphasize the critical figure in a situation.
  • For a successful launch, the magic number is ten thousand pre-orders.

Noun

1. the atomic number of an extra stable strongly bound atomic nucleus: 2, 8, 20, 28, 50, 82 or 126