Energy level

How it is used

The lowest level is the ground state and higher ones are excited states. Energies are often given in electronvolts as negative values, for example −13.6 eV for the ground state of hydrogen. Transitions between levels produce line spectra.

Example sentences

1. An electron falling from the n = 3 to the n = 2 energy level in hydrogen gives off red light.

2. Each element has its own set of energy levels, so each one produces its own line spectrum.

Common collocations

• ground state
• excited state
• energy level diagram
• line spectrum
• electron transition

Related terms

• electronA very light particle with a negative charge of about −1.6 × 10⁻¹⁹ C, found around the nucleus of every atom. Moving electrons carry the current in metal wires.
• photonA single packet, or quantum, of electromagnetic energy. Its energy depends only on the frequency of the radiation: E = hf, where h is Planck's constant.
• quantumThe smallest separate amount of a physical quantity, such as energy, that can be absorbed or emitted. Light energy, for example, comes in quanta called photons.
• atomThe smallest unit of a chemical element, made of a tiny positive nucleus surrounded by negatively charged electrons. Most of an atom is empty space.

More terms: Quantum and Modern Physics

• photoelectric effect
• wave-particle duality
• uncertainty principle
• special relativity