Question

In the following atoms and molecules for the transition from n= 2  to n = 1, the spectral line of minimum wavelength will be produced by

1. Hydrogen atom
2. Uni-ionized Helium
3.  Di-ionized Lithium
4. Deuterium atom

Answer 1

Correct Answer - Option 3 :  Di-ionized Lithium

When an electron jumps from mth orbit to the nth orbit (m>n), the energy of the atom changes from E_m to E_n. This extra energy (E_m - E_n) is emitted as a photon of electromagnetic radiation. This corresponding wavelength is given as

\(\frac{1}{\lambda }\; = \;R{Z^2}\left( {\frac{1}{{{n^2}}} - \frac{1}{{{m^2}}}} \right)\)

Where R is the Rydberg constant = 1.0973 × 107 m^-1

Now for the wavelength to be minimum the Z should be maximum. Out of given options, Z is maximum for Di-ionized Lithium.