Evidence boundary
Use supplied diagrams and numerical models only.
Explicit science instruction
In a simplified energy-level model, electrons occupy allowed states. Moving to a higher state requires absorption of energy that matches the difference between states.
A transition to a lower state can emit a photon with energy equal to the state difference: ΔE = hν.
Modern quantum models describe allowed states and probabilities rather than literal miniature planetary orbits.
Vocabulary: ground state; excited state; transition; Planck constant; photon energy.
Worked example with reasoning
If State B lies 3.0×10⁻¹⁹ J above State A, a B→A transition can emit a photon with energy 3.0×10⁻¹⁹ J. A different photon energy must correspond to a different allowed energy difference.
Guided question
For a diagram with levels at 0, 2, and 5 arbitrary energy units, list every downward transition and its energy difference.
Independent work
- Draw a four-level diagram and label three possible emission transitions.
- Rank the transitions by photon energy.
- Explain how one energy-level diagram can generate several spectral lines.
Misconception check
An electron does not gradually emit every possible energy in this simplified model; allowed transitions correspond to particular energy differences.
Formative understanding check
What determines the energy of an emitted photon in an atomic transition?
Reveal worked response
The energy difference between the initial and final allowed states.
Mentor evidence conference
Ask Archaemenes to test whether your transition diagram and photon-energy ranking are internally consistent.
Teacher guidance
Foundation: Read energy differences from a supplied diagram.
Core: Generate possible transitions and connect them to photons.
Extended: Explain why several transitions can produce a characteristic line spectrum.
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