Chlorine Atomic Number

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Atomic Number of Chlorine is 17.

Chemical symbol for Chlorine is Cl. Number of protons in Chlorine is 17. Atomic weight of Chlorine is 35.45 u or g/mol. Melting point of Chlorine is -34,6 °C and its the boiling point is -101 °C.

» Boiling Point» Melting Point» Abundant» State at STP» Discovery Year

About Chlorine

Relative atomic mass The mass of an atom relative to that of carbon-12. This is approximately the sum of the number of protons and neutrons in the nucleus. Where more than one isotope exists, the value given is the abundance weighted average. Isotopes Atoms of the same element with different numbers of neutrons.

Chlorine has two common isotopes, Chlorine-35 and Chlorine-37. The atomic mass, or as it is properly called, the RELATIVE atomic mass, is a weighted average of the masses of all the isotopes of chlorine. Relative Atomic Mass = (75/100 x 35) + (25/100 x 37) = 35.5. Chlorine (Cl) Atomic Data for Chlorine (Cl) Atomic Number = 17 Atomic Weight = 35.4527 Reference E95: Isotope: Mass: Abundance: Spin: Mag Moment: 35 Cl: 34.968852: 75.77%: 3/2 +0.82187: 37 Cl: 36.965903: 24.23%: 3/2 +0.68412: Cl I Ground State 1s 2 2s 2 2p 6 3s 2 3p 5 2 P.

Chlorine is a light green-yellowish gas, with irritating odor and very toxic properties. The name of this gas is derived from a Greek expression meaning yellow-green. It is one of the oldest known disinfectants as it can very effectively destroy a large number of bacteria. It is very reactive and creates a variety of compounds which are widely used in chemical and other industries. Chlorine is important for life, and we usually take it in small doses from salt. It is impossible to find this chemical element in its pure form in nature; it is usually received from minerals known as halites, which are sodium chlorides. Chloride is used for producing bleach and other disinfectants, especially for disinfecting water. It is also widely used in organic chemistry and in pharmacology, to speed up chemical reactions and manufacturing processes. Chlorine is also used for producing PVC with further use in construction, medicine, car parts, and so on.

Uses of Chlorine


Chlorine (Cl), the second lightest element of the halogens, is mostly used as a disinfectant for drinking water and swimming pools. It also is used in the manufacturing of consumer products such as paper, textiles, contact lenses, solar panels, paints, prosthetics, etc. An important percentage of chlorine is used in making PVC (Polyvinyl chloride) which is a widely produced plastic polymer. PVC is extensively used in manufacturing pipes, electrical cables, building construction, sports clothing and medical devices.

Salt (Sodium chloride), a chemical compound with sodium and chloride ions, is preferred for household purposes, but also used in the production of many chemicals too. Besides, sodium chloride is used in the food industry, agriculture, medicine, the pulp and paper industry. Chlorine is also used on planes, boats and automobiles in the manufacturing of safety belts, airbags, bumpers, dashboards, etc.

Compounds with Chlorine

  • NaCl: Salt (Sodium chloride)
  • C2H3Cl: Vinyl chloride
  • (C2H3Cl)n: Polyvinyl chloride (abbreviated PVC)
  • Cl2O: Dichlorine monoxide
  • NaClO3: Sodium chlorate
  • HOCl: Hypochlorous acid
  • HCl: Hydrogen chloride
  • Ca(ClO)2: Calcium hypochlorite
  • MgCl2: Magnesium dichloride
  • CaCl2: Calcium chloride
  • NH4Cl: Ammonium chloride

Properties of Chlorine Element

Atomic Number (Z)17
Atomic SymbolCl
Atomic Weight35.45 u
Density0.003214 g/cm3
Melting Point (K)171.6 K
Melting Point (℃)-34,6 °C
Boiling Point (K)239.11 K
Boiling Point (℃)-101 °C
Heat Capacity0.479 J/g · K
Abundance145 mg/kg
State at STPGas
Electronegativity (Pauling) χ3.16
Ionization Energy (eV)12.96764
Atomic Radius100pm
Covalent Radius99pm
Van der Waals Radius175
Valence Electrons7
Year of Discovery1774

What is the Boiling Point of Chlorine?

Chlorine boiling point is -101 °C. Boiling point of Chlorine in Kelvin is 239.11 K.

Chlorine Atomic Number Atomic Mass

What is the Melting Point of Chlorine?

Chlorine melting point is -34,6 °C. Melting point of Chlorine in Kelvin is 171.6 K.

Chlorine Atomic Number And Symbol

How Abundant is Chlorine?

Abundant value of Chlorine is 145 mg/kg.

Chlorine Atomic Number Of Neutrons

What is the State of Chlorine at Standard Temperature and Pressure (STP)?

Chlorine Atomic Number

State of Chlorine is Gas at standard temperature and pressure at 0℃ and one atmosphere pressure.

When was Chlorine Discovered?

Chlorine was discovered in 1774.