Exam-style question
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In what scenario would ionisation occur rather than excitation?.
- A.When an electron absorbs a photon with energy equal to or greater than the ionisation energy of the atom.
- B.When an electron absorbs a photon with energy less than the ionisation energy but greater than the excitation energy.
- C.When an electron is struck by a low-energy photon.
- D.When an electron transitions between two energy levels without absorbing energy.
Model answer
What a good answer should say
- When an electron absorbs a photon with energy equal to or greater than the ionisation energy of the atom.
Explanation
Why this works
Ionisation occurs when an electron absorbs enough energy to overcome the attractive forces of the nucleus and is completely removed from the atom. This typically happens when the energy of the absorbed photon is equal to or exceeds the ionisation energy of the atom.
In contrast, excitation occurs with lower energy photons that do not provide enough energy for the electron to escape. Thus, the scenario where ionisation occurs is when the energy threshold is met or exceeded.
Common mistake
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