Electron Configuration

Understanding how electrons are arranged in atoms is fundamental to chemistry. Electron configuration determines an element's chemical properties, the types of bonds it forms, and its position in the periodic table. In this lesson, we will build up electron configurations from first principles.

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Energy Levels and Subshells

Electrons in atoms occupy energy levels (also called shells), numbered n = 1, 2, 3, 4, and so on. The higher the value of n, the further the electron is from the nucleus and the higher its energy.

Each energy level contains one or more subshells, labelled s, p, d, and f:

Energy Level (n)	Subshells Available	Maximum Electrons
1	1s	2
2	2s, 2p	8
3	3s, 3p, 3d	18
4	4s, 4p, 4d, 4f	32

Each subshell contains a specific number of orbitals, and each orbital holds a maximum of 2 electrons (with opposite spins):