quantum number(redirected from Q number)
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quantum numberOne of a set of integers or half integers characterizing the energy states of an elementary particle or system of particles. Physical properties, such as charge and spin, are described by quantum numbers.
quantum number[′kwän·təm ‚nəm·bər]
One of the quantities, usually discrete with integer or half-integer values, needed to characterize a quantum state of a physical system; they are usually eigenvalues of quantum-mechanical operators or integers sequentially assigned to these eigenvalues.