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In quantum physics and chemistry, quantum numbers are quantities that characterize the possible states of the system. To fully specify the state of the electron in a hydrogen atom, four quantum numbers are needed. The traditional set of quantum numbers includes the principal, azimuthal, magnetic, and spin quantum numbers. To describe other ...
The four quantum numbers n, ℓ, m, and s specify the complete and unique quantum state of a single electron in an atom, called its wave function or orbital. Two electrons belonging to the same atom cannot have the same values for all four quantum numbers, due to the Pauli exclusion principle .
Quantum mechanics is a fundamental theory that describes the behavior of nature at and below the scale of atoms. [2]: 1.1 It is the foundation of all quantum physics, which includes quantum chemistry, quantum field theory, quantum technology, and quantum information science. Quantum mechanics can describe many systems that classical physics cannot.
Degenerate states are also obtained when the sum of squares of quantum numbers corresponding to different energy levels are the same. For example, the three states (n x = 7, n y = 1), (n x = 1, n y = 7) and (n x = n y = 5) all have = and constitute a degenerate set.
Each type of nucleus is called a "nuclide", and each nuclide is defined by the specific number of each type of nucleon. "Isotopes" are nuclides which have the same number of protons but differing numbers of neutrons. Conversely, "isotones" are nuclides which have the same number of neutrons but differing numbers of protons.
In the case of electrons in atoms, the exclusion principle can be stated as follows: in a poly-electron atom it is impossible for any two electrons to have the same two values of all four of their quantum numbers, which are: n, the principal quantum number; ℓ, the azimuthal quantum number; m ℓ, the magnetic quantum number; and m s, the spin ...
[4]: 268 The wave function is a complex-valued function of any complete set of commuting or compatible degrees of freedom. For example, one set could be the ,, spatial coordinates of an electron. Preparing a system by measuring the complete set of compatible observables produces a pure quantum state.
Here A = {−s, −s + 1, ..., s − 1, s} is the set of allowed spin quantum numbers and Ω = R 3 is the set of all possible particle positions throughout 3d position space. An alternative choice is α = (s y) for the spin quantum number along the y direction and ω = (p x, p y, p z) for the particle's momentum components.