Barium (Z = 56) has two electrons in the p-shell (valance shell). What are the maximum number of electrons in the penultimate shell i.e O-shell?

Barium (Z = 56) has two electrons in the p-shell (valance shell). What are the maximum number of electrons in the penultimate shell i.e O-shell?

Explanation

Barium (Z = 56) → Electron configuration:

[Xe]6s²

Barium's electron distribution:

  • K = 2
  • L = 8
  • M = 18
  • N = 18 ⬅ Penultimate shell (4th shell / N-shell)
  • O = 8 (valence shell)

The penultimate shell (N-shell) holds 18 electrons in Barium.