Which region of the electromagnetic spectrum does the Lyman series of electron transitions in hydrogen primarily occupy?

• A. Ultraviolet
• B. Microwave
• C. Visible
• D. Infrared

Answer: (A)

Verified step by step guidance

1. Understand that the Lyman series corresponds to electronic transitions in a hydrogen atom where the electron falls to the n=1 energy level from higher levels (n > 1).
2. Recall that the energy difference between levels in the hydrogen atom is given by the formula: \(\Delta E = -13.6 \left( \frac{1}{n_f^2} - \frac{1}{n_i^2} \right)\) eV, where \(n_f\) is the final energy level and \(n_i\) is the initial energy level.
3. Recognize that the Lyman series involves transitions to \(n_f = 1\), which results in relatively large energy differences compared to transitions to higher \(n_f\) levels.
4. Use the relationship between energy and wavelength of emitted photons: \(E = \frac{hc}{\lambda}\), where \(h\) is Planck's constant, \(c\) is the speed of light, and \(\lambda\) is the wavelength.
5. Since the energy differences are large, the emitted photons have short wavelengths, placing the Lyman series in the ultraviolet region of the electromagnetic spectrum.