Chlorine (Cl)

Chlorine is a chemical element of the periodic table with chemical symbol Cl and atomic number 17 with an atomic weight of 35.446 u and is classed as nonmetal and is part of group 17 (fluorine group). Chlorine is gas at room temperature.

Sulfur Periodic table Argon

Chlorine in the periodic table

Symbol	Cl
Atomic number	17
Group	17 (Fluorine group)
Period	3
Block	p
Classification	Nonmetal

Appearance	Pale yellow-green gas
Color	Yellow

Number of protons	17 p⁺
Number of neutrons	18 n⁰
Number of electrons	17 e^-

From Wikipedia, the free encyclopediaChlorine 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.

Physical properties

Phase at STP	Gas
Density	3.2 g/cm³
Atomic weight	35.446 u

Thermal properties

Melting point	171.6 K -101.55 °C -150.79 °F
Boiling point	239.11 K -34.04 °C -29.272 °F
Heat of vaporization	10.2 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)	3.16
Electron affinity	348.575 kJ/mol
Oxidation states	−1, +1, +2, +3, +4, +5, +6, +7 (a strongly acidic oxide)
Ionization energies	1251.2 kJ/mol 2298 kJ/mol 3822 kJ/mol 5158.6 kJ/mol 6542 kJ/mol 9362 kJ/mol 11018 kJ/mol 33604 kJ/mol 38600 kJ/mol 43961 kJ/mol 51068 kJ/mol 57119 kJ/mol 63363 kJ/mol 72341 kJ/mol 78095 kJ/mol 352994 kJ/mol 380760 kJ/mol

Electron configuration for chlorine

Electron configuration

Shorthand configuration

[Ne] 3s² 3p⁵

Electron configuration

Full configuration

1s² 2s² 2p⁶ 3s² 3p⁵

Electron configuration chart

1s²
2s²	2p⁶
3s²	3p⁵

Electrons per shell

2, 8, 7

Valence electrons

7

Valency electrons

1

Bohr model

Figure: Shell diagram of Chlorine (Cl) atom.

Orbital Diagram

1s
2s		2p
3s		3p

The history of Chlorine

Discovery and first isolation	Carl Wilhelm Scheele (1774)
Named by	Sir Humphry Davy (1810)
Recognized as an element by	Humphry Davy (1808)
Discovery of chlorine Chlorine played an important role in the experiments conducted by medieval alchemists, which commonly involved the heating of chloride salts like ammonium chloride (sal ammoniac) and sodium chloride (common salt), producing various chemical substances containing chlorine such as hydrogen chloride, mercury(II) chloride (corrosive sublimate), and hydrochloric acid (in the form of aqua regia). However, the nature of free chlorine gas as a separate substance was only recognised around 1630 by Jan Baptist van Helmont. Carl Wilhelm Scheele wrote a description of chlorine gas in 1774, supposing it to be an oxide of a new element. In 1809, chemists suggested that the gas might be a pure element, and this was confirmed by Sir Humphry Davy in 1810, who named it after the Ancient Greek χλωρός (khlōrós, "pale green") because of its colour.

Periodic table history

Identifiers

List of unique identifiers for Chlorine in various chemical registry databases

CAS Number	7782-50-5
ChemSpider ID	4514529
EC number	231-959-5
PubChem CID Number	24526