The shells around the nucleus are called energy levels. Why?

• Electrons are subatomic particles that move around a nucleus in fixed orbitals called energy levels.
• These levels or orbits are represented with definite letters, K, L, M, N, and so on.

Electronic levels:

• A particular amount of energy is related to each electron revolving in a shell.
• The energy changes when it transfers to another shell and when it goes from one energy level to another.
• Shells are also known as energy levels as they show an electron's energy as well as its location.
• Near the nucleus, electrons have much less energy than all those that are further away.
• To explain the behavior of electrons, the idea of an electronic shell is used.