17 Cl 35.45

Chlorine

diatomic nonmetal

Properties

Atomic number
17
Atomic mass
35.45 u
Category
diatomic nonmetal
Group
17
Period
3
Block
p-block
State (room temp)
Gas
Outer-shell electrons
7
Electronegativity
3.16 (Pauling)
Density
-
Melting point
-101.55 °C
Boiling point
-34.04 °C

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁵

Noble-gas shorthand: [Ne] 3s² 3p⁵

Electrons per shell: 2, 8, 7, which is 7 in the outermost shell.

Related: electron configuration, the Bohr model, valence electrons.

Cl
Bohr model; outer-shell electrons in blue

About Chlorine

Chlorine is a chemical element with symbol Cl and atomic number 17. It also has a relative atomic mass of 35.5. Chlorine is in the halogen group (17) and is the second lightest halogen following fluorine.

Chlorine: frequently asked questions

What is Chlorine?
Chlorine (Cl) is the chemical element with atomic number 17. It is a nonmetal (diatomic nonmetal).
What is the atomic number of Chlorine?
Chlorine's atomic number is 17, which means every Chlorine atom has 17 protons in its nucleus.
What is the electron configuration of Chlorine?
The electron configuration of Chlorine is 1s2 2s2 2p6 3s2 3p5 (noble-gas shorthand: [Ne] 3s2 3p5). Its electrons are arranged in shells of 2, 8, 7, with 7 in the outermost shell.
Is Chlorine a metal or a nonmetal?
Chlorine is a nonmetal (diatomic nonmetal).
What group and period is Chlorine in?
Chlorine is in group 17 and period 3 of the periodic table.
Is Chlorine a solid, liquid, or gas?
At room temperature, Chlorine is a gas.

Position in the periodic table

Open the interactive periodic table →

Data compiled from Wikipedia, PubChem, and IUPAC. Source.