No. Chlorine is a nonmetal, classified as a halogen on the periodic table.

How many protons does chlorine have?

Chlorine has 17 protons. Its atomic number is 17, which is also the number of electrons in a neutral atom of chlorine.

What group and period is chlorine in?

Chlorine is in group 17 and period 3 of the periodic table, in the p-block.

What is the atomic mass of chlorine?

The atomic mass of chlorine is 35.45 u (unified atomic mass units).

Element 17

Chlorine (Cl)

Halogen · Period 3 · Group 17 · p-block

Chlorine (Cl) is element 17 of the periodic table, a halogen in period 3, group 17 (p-block) with an atomic mass of 35.45 and is a gas at standard conditions.

At a glance

Atomic number: 17
Symbol: Cl
Atomic mass: 35.45 u
Category: Halogens
Period: 3
Group: 17
Block: p-block
Phase at STP: gas

Electron structure

Electron configuration: 1s2 2s2 2p6 3s2 3p5
Shorthand configuration: [Ne] 3s2 3p5
Electrons per shell: 2, 8, 7
Oxidation states: -1, +1, +2, +3, +4, +5, +6, +7

Physical properties

Melting point: 171.6 K (-101.55 °C)
Boiling point: 239.11 K (-34.04 °C)
Density: 0.003214 g/cm³
Phase: gas

Atomic properties

Electronegativity (Pauling): 3.16
Atomic radius: 79 pm
Covalent radius: 102 pm
Van der Waals radius: 175 pm
First ionization energy: 1251 kJ/mol
Electron affinity: 349 kJ/mol

Notable isotopes

Notable isotopes of Chlorine: mass number, atomic mass, natural abundance, and stability.
Isotope	Mass	Abundance	Stability
Cl-35	34.96885	75.76%	Stable

Common uses

Water treatment
PVC plastic
Disinfectants
Bleach

Discovery

Year: 1774
Discovered by: Carl Wilhelm Scheele
Country: Sweden

Frequently asked questions

Is chlorine a metal?: No. Chlorine is a nonmetal, classified as a halogen on the periodic table.
How many protons does chlorine have?: Chlorine has 17 protons. Its atomic number is 17, which is also the number of electrons in a neutral atom of chlorine.
What group and period is chlorine in?: Chlorine is in group 17 and period 3 of the periodic table, in the p-block.
What is the atomic mass of chlorine?: The atomic mass of chlorine is 35.45 u (unified atomic mass units).

Keep exploring

Chlorine's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.