Electron configuration

Definition

Electron configuration describes the distribution of electrons in an atom's orbitals. It follows principles such as the Aufbau principle, Pauli exclusion principle, and Hund's rule.

5 Must Know Facts For Your Next Test

1. Electrons fill orbitals starting from the lowest energy level to higher ones according to the Aufbau principle.
2. The Pauli exclusion principle states that no two electrons in the same atom can have identical quantum numbers.
3. Hund's rule specifies that electrons will fill degenerate orbitals (orbitals of the same energy) singly before pairing up.
4. The electron configuration of an element determines its position in the periodic table and its chemical properties.
5. Electron configurations can be represented using notation that indicates the energy levels, subshells, and number of electrons (e.g., $1s^2 2s^2 2p^6$).

Review Questions

• What is Hund\'s rule and how does it affect electron configuration?
• How do you determine the electron configuration for a given element?
• Explain how electron configurations relate to an element\'s chemical properties.

Related terms

Aufbau Principle:

A guideline for determining the electron configuration of an atom, stating that electrons occupy orbitals starting from the lowest available energy levels before filling higher levels.

Pauli Exclusion Principle:

A quantum mechanical principle stating that no two electrons in an atom can have identical sets of four quantum numbers.

Hund's Rule:

A rule stating that every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied.