Atomic energy levels
- Electrons in an atom can have only certain specific (discrete) energies
- These energies are called electron energy levels
- They can be represented as a series of stacked horizontal lines increasing in energy
- Normally, electrons occupy the lowest energy level available, this is known as the ground state
- Electrons can gain energy and move up the energy levels if they absorb energy by:
- Collisions with other atoms or electrons
- Absorbing a photon
- A physical source, such as heat
- This is known as excitation, and when electrons move up an energy level, they are said to be in an excited state
- If the electron gains enough energy to be removed from the atom entirely, this is known as ionisation
- When an electron returns to a lower energy state from a higher excited state, it releases energy in the form of a photon
Electron energy levels in atomic hydrogen
Photons are emitted when an electron moves from a higher energy state to a lower energy state
