If the empirical formula for the observed wavelengths (λ)for hydrogen is 1/λ = R(1/2² - 1/n²), where 'n' is integral values higher than 2, then it represents the _____________ spectral series.

CONCEPT:

• When atoms are excited they emit light of certain wavelengths that correspond to different colors Due to the electron making transitions between two energy levels in an atom.
• The light emission can be seen as a series of colored lines, known as atomic spectra.
  • These atomic spectra are divided into a number of spectral series. The wavelength related to these series is given by the Rydberg formula.
  • The energy differences between levels in the Bohr model is given by the Rydberg formula. Hence the wavelengths of emitted/absorbed photons

\({\displaystyle {1 \over \lambda }=Z^{2}R_{∞ }\left({1 \over {n_{1}}^{2}}-{1 \over {n_{2}}^{2}}\right)}\)

In the Bohr model, spectrum series are given below:

• The Lyman series: It includes the lines emitted by transitions of the electron from an outer orbit of quantum number n2 > 1 to the 1st orbit of quantum number n₁ = 1.
  • All the energy wavelengths in the Lyman series lie in the ultraviolet band.
• The Balmer series: It includes the lines due to transitions from an outer orbit n2 > 2 to the orbit n1 = 2.
  • Four of the Balmer lines lie in the "visible" part of the spectrum.

• Paschen series (Bohr series, n1 = 3)
• Brackett series (n1 = 4)
• Pfund series (n1 = 5)​

EXPLANATION:

• Balmer Series: When an electron in a Hydrogen atom transit from higher energy orbit to 2nd orbit. (outer orbit n2 = n > 2 to the orbit n1 = 2) known as Balmer Series.

So the empirical formula for the observed wavelengths (λ)for hydrogen is

1/λ = R(1/22 - 1/n2), 

• So the correct answer is option 2.

​

• Pfund and Paschen's series lies in the infrared region, Balmer series lies in the visible region while Lyman series of hydrogen atom lies in the ultraviolet region.