The visible emission lines observed by Balmer all involved nf = 2. (a) Which of the following is the best explanation of why the lines with nf = 3 are not observed in the visible portion of the spectrum: (i) Transitions to nf = 3 are not allowed to happen, (ii) transitions to nf = 3 emit photons in the infrared portion of the spectrum, (iii) transitions to nf = 3 emit photons in the ultraviolet portion of the spectrum, or (iv) transitions to nf = 3 emit photons that are at exactly the same wavelengths as those to nf = 2.

Key Concepts

Balmer Series

The Balmer series refers to the set of spectral lines corresponding to electron transitions from higher energy levels (n > 2) to the second energy level (n = 2) in a hydrogen atom. These transitions result in the emission of visible light, which is why the Balmer series is significant in spectroscopy. The visible lines are specifically in the wavelengths that fall within the visible spectrum, making them observable.

Energy Level Transitions

In atomic physics, energy level transitions occur when an electron moves between different energy states within an atom. The energy difference between these levels determines the wavelength of the emitted or absorbed photon. For hydrogen, transitions to the n = 3 level from higher levels do not produce visible light, as they typically correspond to infrared or ultraviolet emissions, depending on the specific transition.

Electromagnetic Spectrum

The electromagnetic spectrum encompasses all types of electromagnetic radiation, ranging from radio waves to gamma rays. The visible portion of the spectrum is a small range of wavelengths that the human eye can detect. Understanding where specific transitions fall within this spectrum is crucial for interpreting spectral lines, as transitions that emit photons outside the visible range (like infrared or ultraviolet) will not be seen in visible light observations.