Let us assume that the electron in the lithium-ion is knocked off from the nth energy level, then
R(ZH)2(121−221)=Rn2(ZLi)2
R(1)2×43=R(3)2[n21]
43=n29
n=12≈3.5
Hence the least quantum number must be 4.
An electron in a hydrogen atom makes a transition from n=2 to n=1 and emits a photon. This photon strikes a doubly ionized lithium atom which was already in an excited state and completely removes the orbiting electron. The least quantum number for the excited state of the lithium-ion for the process is
Held on 9 Apr 2016 · Verified 6 Jul 2026.
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3
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