Key idea
Atomic energy levels
Hydrogène : Eₙ = −13,6 eV / n²
Bound electrons in atoms occupy quantized energy states. Transitions between states can involve absorption or emission of photons whose energies match the energy difference.
Atomic energy levels
The key idea
Bound electrons in atoms occupy quantized energy states. Transitions between states can involve absorption or emission of photons whose energies match the energy difference.
Why it matters
Discrete atomic spectra are direct experimental evidence that atomic energies are not continuous.
A picture to remember
Key idea
Atomic energy levels
Guided example
Atomic energy levels
Bound electrons in atoms occupy quantized energy states. Transitions between states can involve absorption or emission of photons whose energies match the energy difference.
Put it into practice
Atomic energy levels
Choose a concrete case linked to Atomic energy levels. Write down the known information, what you are trying to find, and the units. Then state the rule, model or trend you will use. If a calculation is involved, keep the units visible at every line; if it is conceptual, state what changes and what remains fixed.
Check your answer
A strong answer contains four things: the starting situation, the variable that changes, the direction or numerical result, and one check. The check can be a unit, an order of magnitude, a limiting case or a comparison with a familiar example.