Combination formula | Probability and combinatorics | Probability and Statistics | Khan Academy
There are four possible combinations for values of l and ml for n = 2. The n = 2 principal energy level includes an s orbitals orbitalHistory. The term “orbital” was coined by Robert Mulliken in 1932 as an abbreviation for one-electron orbital wave function.https://en.wikipedia.org › wiki › Atomic_orbitalAtomic orbital – Wikipedia and a p orbital.