Krypton

Krypton (frae [κρυπτός kryptos] "the hidden ane") is a chemical element wi seembol Kr an atomic nummer 36. It is a member o group 18 (noble gases) elements. A colourless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere, is isolatit bi fractionally distillin liquified air, an is eften uised wi ither rare gases in fluorescent lamps. Krypton is inert for maist practical purposes.

Krypton, ₃₆Kr

A krypton-filled dischairge tube glowin white
Krypton
Pronunciation	/ˈkrɪptɒn/ ​(KRIP-ton)
Appearance	colourless gas, exhibitin a whitish glow in a heich electric field
Standard atomic weight Ar, std(Kr)	7001837980000000000♠83.798(2)
Mass number	Kr:
Krypton 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 Ar ↑ Kr ↓ Xe bromine ← krypton → rubidium
Atomic nummer (Z)	36
Group	group 18 (noble gases)
Period	period 4
Block	p-block
Element category	Noble gas
Electron confeeguration	[Ar] 3d10 4s2 4p6
Electrons per shell	2, 8, 18, 8
Pheesical properties
Phase at STP	gas
Meltin pynt	115.78 K ​(-157.37 °C, ​-251.27 °F)
Bylin pynt	119.93 K ​(-153.415 °C, ​-244.147 °F)
Density (at STP)	3.749 g/L
whan liquid (at b.p.)	2.413 g/cm3
Treeple pynt	115.775 K, ​73.53 kPa
Creetical pynt	209.48 K, 5.525 MPa
Heat o fusion	1.64 kJ/mol
Heat o vapourisation	9.08 kJ/mol
Molar heat capacity	5R/2 = 20.786 J/(mol·K)
Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 59 65 74 84 99 120
Atomic properties
Oxidation states	0, +1, +2 (rarely mair nor 0; oxide is unknown)
Electronegativity	Pauling scale: 3.00
Covalent radius	116±4 pm
Van der Waals radius	202 pm
Spectral lines o krypton
Ither properties
Naitural occurrence	Kr: Primordial
Creestal structur	​face-centred cubic (fcc)
Speed o soond	(gas, 23 °C) 220, (liquid) 1120 m/s
Thermal conductivity	9.43×10-3  W/(m·K)
Magnetic orderin	diamagnetic
CAS Nummer	7439-90-9
History
Diskivery	William Ramsay an Morris Travers (1898)
First isolation	William Ramsay an Morris Travers (1898)
Main isotopes o krypton
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 78Kr 0.35% >1.1×1020 y (β+β+) 78Se 79Kr syn 35.04 h ε 79Br β+ 79Br γ - 80Kr 2.25% stable 81Kr trace 2.29×105 y ε 81Br γ - 82Kr 11.6% stable 83Kr 11.5% stable 84Kr 57.0% stable 85Kr syn 10.756 y β− 85Rb 86Kr 17.3% - (β−β−) 86Sr
Decay modes in parentheses are predictit, but hae nae yet been observed