Atomic orbital

An atomic orbital is a state an electron in an isolated atom can be in.

Orbitals are commonly specified as eigenstates defined by their energy and angular momentum, the quantum numbers n and l.

In an atom, orbitals fill in order of increasing n+l, and then increasing n.

List of orbitals

  • (n,l)=(0,0) (1s) holds 4 electrons (see spin)
  • 1,0 (2s) holds 4 electrons
  • 1,1 (2p) holds 20 electrons
  • 2,0 (3s) holds 4 electrons
  • 2,1 (3p) holds 20 electrons
  • 2,2a (3d0) holds 40 electrons
  • 2,2b (3d1) holds 56 electrons

The 3d0 and 3d1 orbitals are very similar, which results in the splitting phenomenon.