Q.

Consider a hydrogen-like ionized atom with atomic number Z with a single electron. In the emission spectrum of this atom, the photon emitted in the n=2 to n=1 transition has energy 74.8 eV higher than the photon emitted in the n=3 to n=2 transition. The ionization energy of the hydrogen atom is 13.6 eV. The value of Z is ______.     [2018]


Ans.

(3)

According to the question, the photon emitted in the n=2→n=1 transition has energy 74.8 eV higher than the photon emitted in the n=3→n=2 transition.

∴  ΔE2→1=74.8+ΔE3→2

13.6Z2(1-14)=74.8+13.6Z2(14-19)

∴  Z=3