Chlorine

Chlorine is a chemical element wi seembol Cl an atomic nummer 17. Chlorine is in the noble gas group (17) an is the seicont lichtest alkali metal after 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.

Chlorine, ₁₇Cl

Chlorine
Pronunciation	/ˈklɔːriːn/ ​(KLOR-een)
Appearance	fauch yellae-green gas
Standard atomic weight Ar, std(Cl)	[7001354460000000000♠35.446, 7001354570000000000♠35.457] conventional: 7001354500000000000♠35.45
Chlorine in the periodic cairt
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium F ↑ Cl ↓ Br sulfur ← chlorine → argon
Atomic nummer (Z)	17
Group	group 17 (halogens)
Period	period 3
Block	p-block
Element category	Reactive nonmetal
Electron confeeguration	[Ne] 3s2 3p5
Electrons per shell	2, 8, 7
Pheesical properties
Phase at STP	gas
Meltin pynt	171.6 K ​(-101.5 °C, ​-150.7 °F)
Bylin pynt	239.11 K ​(-34.04 °C, ​-29.27 °F)
Density (at STP)	3.2 g/L
whan 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 vapourisation	(Cl2) 20.41 kJ/mol
Molar heat capacity	(Cl2) 33.949 J/(mol·K)
Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 128 139 153 170 197 239
Atomic properties
Oxidation states	−1, +1, +2, +3, +4, +5, +6, +7 strangly acidic
Electronegativity	Pauling scale: 3.16
Ionisation energies	(more)
Covalent radius	102±4 pm
Van der Waals radius	175 pm
Colour lines in a spectral range Spectral lines o chlorine
Ither properties
Naitural occurrence	primordial
Creestal 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 Nummer	7782-50-5
History
Diskivery	Carl Wilhelm Scheele (1774)
First isolation	Carl Wilhelm Scheele (1774)
Recognised as an element bi	Humphry Davy (1808)
Main isotopes o chlorine
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 35Cl 75.77% stable 36Cl trace 3.01×105 y β− 36Ar ε 36S 37Cl 24.23% stable