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Concept module

Bohr Model

Use a compact hydrogen bench to connect quantized energy levels, allowed transitions, and named spectral-line series while staying clear that Bohr is a useful historical model rather than the final quantum description.

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Starter track

Step 4 of 50 / 5 complete

Modern Physics

Earlier steps still set up Bohr Model.

1. Photoelectric Effect2. Atomic Spectra3. de Broglie Matter Waves4. Bohr Model+1 more steps

Previous step: de Broglie Matter Waves.

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Why it behaves this way

Explanation

The Bohr model is a bounded historical hydrogen model: it gives electrons only certain allowed energy levels, so light comes from discrete transitions rather than from any arbitrary orbital drop. That makes it a strong bridge from observed line spectra to quantized atomic structure without pretending to be the final quantum description.

This module keeps one compact bench with a radius map, an energy ladder, a hydrogen line map, and one wavelength graph. The selected transition, its wavelength, its series family, its reverse excitation case, the worked examples, quick tests, and challenge checks all stay tied to that same live state.

Key ideas

01For hydrogen in the Bohr model, the allowed energies follow E_n = -13.6 eV / n^2, so only certain transition gaps exist.
02Holding the lower level fixed creates named hydrogen series such as Lyman, Balmer, and Paschen.
03Within one series, higher starting levels crowd the lines toward a series limit because the upper energies bunch closer together.
04This page treats Bohr as a useful historical and conceptual model for hydrogen spectral lines, not as the final quantum-mechanical picture.

Frozen walkthrough

Step through the frozen example

Frozen walkthrough
Use the current hydrogen transition directly from the live bench. The same levels, graph, overlays, and readout card drive each worked result.

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Frozen valuesUsing frozen parameters

For the current transition 3 -> 2, what photon energy and wavelength belong to this Bohr jump?

Upper level

3

Lower level

2

Transition energy

1.89 eV eV

Photon wavelength

656.39 nm nm

1. Identify the live jump

The bench is currently showing 3 -> 2, so the electron changes between n = 3 and n = 2.

2. Read the quantized gap

That allowed hydrogen gap is 1.89 eV on the live ladder and readout card.

3. Convert the gap to a photon wavelength

Using , this jump gives 656.39 nm in the Visible.

Current transition

This Balmer transition lands in visible red, so the line sits inside the same wavelength window the graph and strip highlight together.

Hydrogen-line checkpoint

Why do 3 -> 2 emission and 2 -> 3 excitation use the same wavelength on this page even though one arrow points down and the other points up?

Make a prediction before you reveal the next step.

Answer from the allowed energy gap, not from arrow direction alone.

Check your reasoning against the live bench.

They use the same wavelength because both processes involve the same energy difference between the same two allowed levels. Emission releases that photon energy, and excitation requires that same photon energy.
The direction changes whether the atom gives the photon energy away or absorbs it, but the magnitude of the allowed gap stays fixed.

Common misconception

If the electron can orbit the nucleus, it should be able to fall from any radius to any other and emit any color you want.

In the bounded Bohr model, only specific energy levels are allowed, so only specific transition gaps and wavelengths appear.

Modern quantum mechanics replaces the literal orbit picture, but the quantized-level idea still explains why hydrogen line spectra are discrete.

Quick test

Reasoning

Question 1 of 4

Answer from the live hydrogen-level story, not from disconnected historical slogans.

Why does the Bohr-model page show discrete hydrogen lines instead of every wavelength?

Use the live bench to test the result before moving on.

Accessibility

The simulation shows a compact Bohr-model hydrogen bench with a radius map on the left, an energy ladder in the middle, and a hydrogen line strip on the right. A highlighted arrow marks the active transition, and a matching wavelength marker appears on the strip and graph.

Optional overlays label the line family, the allowed wavelengths, the n squared radius scaling, and the matching reverse-excitation wavelength. The readout card summarizes the current mode, series name, active level pair, photon energy, wavelength, series limit, and radius ratio.

Graph summary

The graph plots relative line strength against wavelength across ultraviolet, visible, and infrared regions for the selected hydrogen series. Narrow peaks mark the allowed series lines, and the active transition is read from the same wavelength axis used by the strip.