Shells

Definition

Shells are energy levels in an atom where electrons reside. They are designated by the principal quantum number $n$ and determine the atom's electron configuration.

5 Must Know Facts For Your Next Test

1. Shells are denoted by integers (1, 2, 3, etc.) corresponding to the principal quantum number $n$.
2. The maximum number of electrons a shell can hold is given by the formula $2n^2$.
3. Higher-numbered shells have higher energy and are farther from the nucleus.
4. Electrons in higher shells have greater potential energy due to their distance from the nucleus.
5. The arrangement of electrons within these shells determines an element's chemical properties.

Review Questions

• What is the relationship between the principal quantum number $n$ and the energy level of a shell?
• How do you calculate the maximum number of electrons that can occupy a given shell?
• Why do electrons in higher-numbered shells have more potential energy?

Related terms

Principal Quantum Number: A number ($n$) that specifies the energy level or shell of an electron in an atom.

Electron Configuration: The distribution of electrons among the various orbitals of an atom.

Orbital: A region in space around a nucleus where an electron is likely to be found; each orbital can hold up to two electrons.