Electron Configuration of Chlorine (Cl)

What is the electron configuration of Chlorine?

The electron configuration of Chlorine (Cl, Z=17) is 1s² 2s² 2p⁶ 3s² 3p⁵. In noble gas shorthand: [Ne] 3s² 3p⁵. It has 1 unpaired electron(s) and is a p-block element.

SymbolCl
Atomic Number17
Full Electron Configuration1s² 2s² 2p⁶ 3s² 3p⁵
Noble Gas Shorthand[Ne] 3s² 3p⁵
Blockp
Period3
Group17
Unpaired Electrons1
Exception?No

Orbital Filling Order

Following the aufbau principle, the 17 electrons in Chlorine fill orbitals in order of increasing energy: 1s (2 electrons), then 2s (2 electrons), then 2p (6 electrons), then 3s (2 electrons), then 3p (5 electrons).

Each orbital is filled according to the Pauli exclusion principle (at most 2 electrons per orbital) and Hund's rule (electrons occupy degenerate orbitals singly before pairing).

Noble Gas Shorthand

The inner electrons of Chlorine match the configuration of Ne. This allows us to abbreviate the configuration as [Ne] 3s² 3p⁵, where [Ne] represents the filled core and the remaining entries show the valence electrons.

Valence Electrons

The valence shell of Chlorine contains 2 electrons in the 3s subshell and 5 electrons in the 3p subshell. These outermost electrons determine Chlorine's chemical reactivity, bonding behavior, and position in the periodic table as a p-block element in period 3.

Visualize orbital filling with 3D orbital shapes, aufbau principle, and noble gas shorthand for 36 elements.

Explore Chlorine in the Electron Configuration Explorer

Related Topics

Electron Configuration of Sodium

Orbital filling and noble gas shorthand for Sodium

Electron Configuration of Magnesium

Orbital filling and noble gas shorthand for Magnesium

Electron Configuration of Carbon

Orbital filling for Carbon (p-block)

Electron Configuration of Neon

Orbital filling for Neon (p-block)

Chlorine on the Periodic Table

Full properties and periodic trends for Chlorine

Orbital Hybridization

See how atomic orbitals mix to form sp, sp2, and sp3 hybrids