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What's the difference between "ortibal" and "orbit"? Which one should be used in physics? In quantum mechanics, is "atomic orbital" or "atomic orbit" used? And what about in classical mechanics? A particle's orbit or orbital?

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up vote 6 down vote accepted

An orbit is a closed trajectory of a classical dynamical system. Properties of orbits or related to orbits are referred to as orbital properties.

An orbital is a single-electron wave function for an atom or molecule in the Hartree-Fock approximation. (There are also hybrid orbitals for electron pairs in a chemical bond.)

Thus a particle has an orbit (and related properties such as orbital speed) if it is treated classically (e.g., a planet). But if treated by quantum mechanics (e.g., an electron), it instead has orbitals.

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The first link doesn't work since the closing parenthesis is lost. How to fix this? – Arnold Neumaier Sep 3 '12 at 17:33
You can put angle brackets around the link - I fixed it for you. – David Z Sep 3 '12 at 17:50

In quantum mechanics, strictly speaking, it's usually "orbital" ( ), in classical mechanics, it's "orbit". But classical mechanics is not very good for atoms.

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