The Quantum Mechanical Model of the Atom

The modern, more complete picture of where electrons are found in an atom.

Quantum Numbers

Four quantum numbers describe the position and energy of an electron in an atom: Principal (n), Azimuthal (l), Magnetic (m), and Spin (s).

Filling Electrons into Orbitals

  • Aufbau Principle — electrons fill orbitals in order of increasing energy
  • Pauli Exclusion Principle — no two electrons in an atom can have the same set of four quantum numbers
  • Hund's Rule — electrons fill degenerate orbitals singly before pairing up
Lesson 6 of 26
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