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Bohr angular momentum
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Atomic angular momentum is quantised.
L = nħBohr's model states that electron angular momentum is quantised in units of ħ: L = nħ. In quantum mechanics orbital angular momentum is √(l(l+1))ħ.
n = 2 gives L = 2ħ.
Modern theory modifies the Bohr numbers.
In more detail
In the Bohr model, an electron's angular momentum is quantised in units of h divided by 2π. This quantisation sets the allowed orbits and energy levels of the hydrogen atom.
Real-world uses
- The Bohr model explains the spectral lines of hydrogen, which are used in astronomy.
- Quantised angular momentum underlies the structure of atoms and molecules.
- Early models of the atom, such as Bohr's, explain the spectra of hydrogen by quantising the angular momentum of the electron.
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Frequently asked questions
Is the Bohr model still used?
As an introduction it is valuable, but quantum mechanics gives a more complete description.
Why is angular momentum quantised?
It is a consequence of wave behaviour of electrons, which must fit in whole numbers of wavelengths around the orbit.
Why is angular momentum quantised?
In the atom, only certain values of angular momentum are allowed, which leads to discrete energy levels and spectral lines.
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