Editing Azimuthal quantum number (section)

== History ==
The azimuthal quantum number was carried over from the [[Bohr model|Bohr model of the atom]], and was posited by [[Arnold Sommerfeld]].<ref>{{cite book|last=Eisberg|first=Robert|title=Quantum Physics of Atoms, Molecules, Solids, Nuclei and Particles | year=1974|publisher=John Wiley & Sons Inc|location=New York|isbn=978-0-471-23464-7|pages=114–117}}</ref> The Bohr model was derived from [[spectroscopy|spectroscopic analysis]] of atoms in combination with the [[Ernest Rutherford|Rutherford]] atomic model.  The lowest quantum level was found to have an angular momentum of zero.  Orbits with zero angular momentum were considered as oscillating charges in one dimension and so described as "pendulum" orbits, but were not found in nature.<ref>{{cite journal|title=Note on "pendulum" orbits in atomic models |journal=Proc. Natl. Acad. Sci. |year=1927 |volume=13 |pages=413–419 |pmid=16587189 |author=R.B. Lindsay |issue=6 |author-link=Robert Bruce Lindsay |doi=10.1073/pnas.13.6.413 |bibcode=1927PNAS...13..413L |pmc=1085028|doi-access=free }}</ref> In three-dimensions the orbits become spherical without any [[Node (physics)|nodes]] crossing the nucleus, similar (in the lowest-energy state) to a skipping rope that oscillates in one large circle.