Ask A Scientist Chemistry Archive

name         Erica H.
status       student
age          14

Question -   Why do the energy levels of an atom start with the
letter K? Followed by L,M,N,O, and so on...
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That is an accident of history. Linus Pauling in his chemistry text
"General Chemistry" 1988 edition publ. by Dover pg. 129: "...English
physicist Charles Glover Barkla measured the power of x-rays to penetrate...
various substances and discovered that elements emit characteristic x-rays
of two kinds, differing in their penetrating power. After having used the
letters B and A, he decided in 1911 to assign K to the most penetrating and
L to less penetrating radiation, in order to leave letters available for
still more or less penetrating kinds of characteristic radiation, which he
thought would probably be discovered."
See the citation for some more details.

Vince Calder
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