Chlorine

Chlorine,  ₁₇Cl

General properties
Name, seembol	chlorine, Cl
Pronunciation	/ˈklɔəriːn/ KLOHR-een or /ˈklɔərɨn/ KLOHR-ən
Appearance	pale yellae-green gas
Chlorine in the periodic cairt
F ↑ Cl ↓ Br sulfur ← chlorine → argon
Atomic nummer	17
Staundart atomic wicht (±) (Ar)	35.45(1)
Element category	diatomic nonmetal
Group, block	group 17 (halogens), p-block
Period	period 3
Electron configuration	[Ne] 3s2 3p5
per shell	2, 8, 7
Pheesical properties
Phase	gas
Meltin pynt	171.6 K ​(-101.5 °C, ​-150.7 °F)
Boilin pynt	239.11 K ​(-34.04 °C, ​-29.27 °F)
Density at stp (0 °C an 101.325 kPa)	3.2 g/L
when liquid, at b.p.	1.5625 g/cm3
Creetical pynt	416.9 K, 7.991 MPa
Heat o fusion	(Cl2) 6.406 kJ/mol
Heat o	(Cl2) 20.41 kJ/mol
Molar heat capacity	(Cl2) 33.949 J/(mol·K)
pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 128 139 153 170 197 239
Atomic properties
Oxidation states	7, 6, 5, 4, 3, 2, 1, -1 ​strangly acidic oxide
Electronegativity	Pauling scale: 3.16
energies	(mair)
Covalent radius	102±4 pm
Van der Waals radius	175 pm
Miscellanea
Crystal structur	​orthorhombic
Speed o soond	(gas, 0 °C) 206 m/s
Thermal conductivity	8.9×10−3  W/(m·K)
Electrical resistivity	> 10  Ω·m (at 20 °C)
Magnetic orderin	diamagnetic
CAS Registry Nummer	7782-50-5
History
Discovery	Carl Wilhelm Scheele (1774)
First isolation	Carl Wilhelm Scheele (1774)
Recognized as an element bi	Humphry Davy (1808)
Maist stable isotopes
iso NA hauf-life DM DE (MeV) DP 35Cl 75.77% 35Cl is stable wi 18 neutrons 36Cl trace 3.01×105 y β− 0.709 36Ar ε - 36S 37Cl 24.23% 37Cl is stable wi 20 neutrons

Chlorine is a chemical element wi seembol Cl an atomic nummer 17. Chlorine is in the halogen group (17) an is the seicont lichtest halogen efter fluorine. The element is a yellae-green gas unner staundart condeetions, whaur it furms diatomic molecules. It haes the heichest electron affinity an the third heichest electronegativity o aw the reactive elements; for this reason, chlorine is a strang oxidizin agent. Free chlorine is rare on Yird, an is uisually a result o direct or indirect oxidation bi oxygen.