22.4 Energy levels in atoms and line spectra

An isolated atom allows electrons only in particular energy states, not every energy between them.

An electron changes level by absorbing or emitting a photon whose energy equals the gap: ΔE=hf. Larger gaps correspond to higher-frequency, shorter-wavelength lines.

A hydrogen emission spectrum contains separate lines because only certain transitions are allowed between its levels.

The electron does not radiate continuously while remaining in a stationary level; emission occurs during a transition between allowed states.

understand the appearance and formation of emission and absorption line spectra.

Use —the appearance and formation of emission and absorption line spectra to connect the rule to the data and decision in the question.

This matters because —the appearance and formation of emission and absorption line spectra determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —the appearance and formation of emission and absorption line spectra to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —The appearance and formation of emission and absorption line spectra is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.

recall and use hf = E1 – E2.

Use —hf = e1 – e2 to connect the rule to the data and decision in the question.

This matters because —hf = e1 – e2 determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply —hf = e1 – e2 to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: —Hf = E1 – E2 is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.