Chemistry - Atomic Structure Question with Solution | TestHub

Excited atoms emits radiations consisting of only certain discrete frequencies or wavelengths. In spectroscopy it is often more convenient to use frequencies or wave number than wavelength because frequencies and wave numbers are proportional to energy, and spectroscopy involves transitions between different energy levels. The line spectrum shown by an mono electronic excited atom ( a finger print of an atom) can be given as.

$$\frac{1}{\lambda }=\bar{v}=R_H\cdot Z^2\left[\frac{1}{n_1^2}-\frac{1}{n_2^2}\right]$$

where Z is atomic number of mono electronic atom and ${\mathrm{n}}_1,{\mathrm{n}}_2$ are integers and if ${\mathrm{n}}_2>{\mathrm{n}}_1$, then emission spectrum is noticed and if ${\mathrm{n}}_2<{\mathrm{n}}_1$, then absorption spectrum is noticed. Every line in spectrum can be represented as a difference of two terms $\frac{{\mathrm{R}}_{\mathrm{H}}{\mathrm{Z}}^2}{{\mathrm{n}}_1^2}$ and $\frac{{\mathrm{R}}_{\mathrm{H}}{\mathrm{Z}}^2}{{\mathrm{n}}_2^2}$.