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Spin-orbit coupling Calculator

Allowed j values from spin-orbit coupling.

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Overview

Spin-orbit coupling combines orbital and spin angular momentum into allowed total-j values.

Symbols

Variables

j = j

j
Variable

Apply it well

When To Use

When to use: Use this when you need hydrogenic quantum numbers or simple bonding pictures for atoms and molecules.

Why it matters: These are the standard quantum-number rules behind shell filling, angular momentum, and orbital shapes.

Avoid these traps

Common Mistakes

  • Confusing orbital orientation with orbital energy.
  • Ignoring spin when counting the number of available states.
  • Mixing up the magnitude of angular momentum with its z-component.

One free problem

Practice Problem

If an electron has an orbital angular momentum quantum number l = 1, what are the possible total angular momentum quantum numbers j?

Solve for:

Hint: Recall that j = l ± s, where s = 1/2 for an electron.

The full worked solution stays in the interactive walkthrough.

References

Sources

  1. Chemistry LibreTexts, hydrogen atom, angular momentum, and bonding orbitals chapters, accessed 2026-04-09
  2. Chemistry LibreTexts, bonding and antibonding orbitals, accessed 2026-04-09
  3. Chemistry LibreTexts, angular momentum in the hydrogen atom, accessed 2026-04-09
  4. Griffiths, David J. (2018). Introduction to Quantum Mechanics (3rd ed.). Cambridge University Press.
  5. Atkins, Peter; de Paula, Julio (2017). Physical Chemistry (11th ed.). Oxford University Press.
  6. Landau, L. D., & Lifshitz, E. M. (1977). Quantum Mechanics: Non-Relativistic Theory (Vol. 3, 3rd ed.). Pergamon Press.
  7. Sakurai, J. J., & Napolitano, J. (2017). Modern Quantum Mechanics (2nd ed.). Cambridge University Press.