Symbol	Cl
Atomnummer	17
Gruppe	17 (Halogener)
Periode	3
Blok	p
Klassifikation	Ikkemetal

Udseende	Pale yellow-green gas
Farve	Gul

Antal protoner	17 p+
Antal neutroner	18 n0
Antal elektroner	17 e-

Fra Wikipedia, den gratis encyklopædiKlor eller chlor (fra latin chlorum) (fra græsk: Xλώριο=chlorós gulligt-grøn) er et grundstof, som er gasformig under normalbetingelser (1,013 bar, 0 °C). Klor lugter stikkende og er klassificeret som farlig stof. Det gulgrønne klor er noget opløseligt i vand, den vandige opløsning kaldes klorvand. Klor optager nemt elektroner og egner sig derfor godt som oxidationsmiddel. I industrien bliver klor nu om dage tit erstattet af det mindre miljøskadelige og nemmere håndterbare stof H₂O₂ (Hydrogenperoxid).

Fase ved STP	Gas
Massefylde	3.2 g/cm3
Atommasse	35.446 u

Smeltepunkt	171.6 K -101.55 °C -150.79 °F
Kogepunkt	239.11 K -34.04 °C -29.272 °F
Fordampningsvarme	10.2 kJ/mol

Elektronegativitet (Pauling Scale)	3.16
Elektronaffinitet	348.575 kJ/mol
Oxidationstrin	−1, +1, +2, +3, +4, +5, +6, +7 (a strongly acidic oxide)
Ioniseringsenergier	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

Elektronkonfiguration Kortfattet konfiguration	[Ne] 3s2 3p5
Elektronkonfiguration Fuld konfiguration	1s2 2s2 2p6 3s2 3p5
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p5
Elektroner pr. Skal	2, 8, 7
Valenselektroner	7
Valency-elektroner	1
Bohrs atommodel	Figur: Skaldiagram af Klor (Cl) atom.
Orbital diagram	1s 2s 2p 3s 3p

Opdagelse og første isolation	Carl Wilhelm Scheele (1774)
Navngivet af	Sir Humphry Davy (1810)
Recognized as an element by	Humphry Davy (1808)
Opdagelse af klor 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.

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