Chemistry · Structure Of Atom · NEET
The Balmer series. It is the only series that gives light your eyes can see. In the Balmer series the electron jumps DOWN to the n = 2 level from a higher level (n = 3, 4, 5, ...). Every other series lands on a different level and gives invisible light.
The visible region needs photon wavelengths of about 400-700 nm. Only the energy gaps for jumps ending at n = 2 fall in this range. Jumps ending at n = 1 (Lyman) are bigger energy gaps, so they give short-wavelength UV light. Jumps ending at n = 3 or higher (Paschen, Brackett, Pfund) are smaller energy gaps, so they give long-wavelength infrared (IR) light. So n = 2 is the "sweet spot" for visible light.
No. The Lyman series ends at n = 1. These jumps release the most energy, so the light has a very short wavelength. That puts it in the ultraviolet (UV) region, which your eyes cannot see. A common NEET trap is to pick Lyman because it is the "first" series, but it is UV, not visible.
All three lie in the infrared (IR) region, which is invisible. Paschen ends at n = 3, Brackett at n = 4, and Pfund at n = 5. As the landing level gets higher, the energy gap gets smaller and the wavelength gets longer, so all of them are IR.
The final (lower) level is n = 2 for all visible lines. The starting level is any higher level: n = 3 gives the H-alpha red line, n = 4 gives H-beta, n = 5 gives H-gamma, and so on. So for the visible region, always remember n(final) = 2.
Most of the bright Balmer lines are visible, but as the starting level goes very high (n = 7, 8, ... to infinity), the lines crowd together near the series limit and slip into the near-UV. For NEET, remember the rule simply: Balmer series = visible region.
Which of the following series of transitions in the spectrum of the hydrogen atom falls in the visible region?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
The Balmer series lies in the visible region, formed by electron jumps down to n = 2.
The Lyman series lies in the ultraviolet (UV) region because it ends at n = 1 and releases high-energy photons.
The Paschen (n = 3), Brackett (n = 4) and Pfund (n = 5) series all lie in the infrared (IR) region.
The final (lower) level is n = 2. The electron falls from n = 3, 4, 5, ... down to n = 2.
NEET often asks you to match a hydrogen series to its spectral region. Remembering that only Balmer (n = 2) is visible lets you answer these one-mark questions instantly.
