BRAINCAKEExcitation and De-excitation
An electron can move up to a higher energy level if it gains exactly the right amount of energy. This is called excitation, and it can happen in two ways.
1. Absorbing a photon. A photon is only absorbed if its energy exactly equals the difference between two energy levels. A photon with any other energy is not absorbed, because a photon cannot give up only part of its energy.
2. Collision with a free electron. A fast-moving electron colliding with an atom can transfer some of its kinetic energy to an atomic electron. The incoming electron only needs at least as much energy as the gap; any extra is kept as kinetic energy.
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Key terms in this lesson
- energy level
- One of the discrete, fixed values of energy that an electron in an atom can have.
- excited state
- An energy level of an electron in an atom that is higher than the ground state.
More in Quantum Physics
- Electron Diffraction
- DeBroglie Wavelength
- Electron Microscopes
- Electron Energy Levels
- Line Spectra
- Exam Question 1
- Exam Question 2
- Exam Question 3
All 21 lessons in Quantum Physics · All Edexcel AS-level Physics topics