I would be delinquent if I failed to mention the archaic nomenclature for atomic states, because all chemists and most physicists use it (and the people who make up the Graduate Record Exam love this sort of thing). For reasons known best to nineteenth-century spectroscopists, l = 0 is called s (for “sharp”), l = 1 is p (for “principal”), l = 2 is d (“diffuse”), and l = 3 is f (“fundamental”); after that I guess they ran out of imagination, because it now continues alphabetically (g, h, i, skip j, just to be utterly perverse, k, l, etc.).¹⁹
[…] There exist rituals, known as Hund’s Rules (see Problem 5.18) for figuring out what these totals will be, for a particular atom. The result is recorded as the following hieroglyphic:
¹⁹: The shells themselves are assigned equally arbitrary nicknames, starting (don’t ask me why) with K : The K shell is n = 1, the L shell is n = 2, M is n = 3, and so on (at least they’re in alphabetical order).
— Introduction to Quantum Mechanics by David J. Griffiths, Darrell F. Schroeter (Page 213 - 214)
I get the feeling the author is not really liking chemistry/the chemists' conventions…