Krypton

Krypton, ₃₆Kr

A krypton-filled discharge tube glowing white
Krypton
Pronunciation	/ˈkrɪptɒn/ ​(KRIP-ton)
Appearance	colorless gas, exhibiting a whitish glow in an electric field
Standard atomic weight Ar°(Kr)
	83.798±0.002[1] 83.798±0.002 (abridged)[2]
Krypton in the periodic table
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 Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver 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 Gold Mercury (element) Thallium Lead 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 Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Ar ↑ Kr ↓ Xe bromine ← krypton → rubidium
Atomic number (Z)	36
Group	group 18 (noble gases)
Period	period 4
Block	p-block
Electron configuration	[Ar] 3d10 4s2 4p6
Electrons per shell	2, 8, 18, 8
Physical properties
Phase at STP	gas
Melting point	115.78 K ​(−157.37 °C, ​−251.27 °F)
Boiling point	119.93 K ​(−153.415 °C, ​−244.147 °F)
Density (at STP)	3.749 g/L
when liquid (at b.p.)	2.413 g/cm3[3]
Triple point	115.775 K, ​73.53 kPa[4][5]
Critical point	209.48 K, 5.525 MPa[5]
Heat of fusion	1.64 kJ/mol
Heat of vaporization	9.08 kJ/mol
Molar heat capacity	20.95[6] J/(mol·K)
Vapor pressure 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 more than 0; oxide is unknown)
Electronegativity	Pauling scale: 3.00
Ionization energies	1st: 1350.8 kJ/mol 2nd: 2350.4 kJ/mol 3rd: 3565 kJ/mol
Covalent radius	116±4 pm
Van der Waals radius	202 pm
Spectral lines of krypton
Other properties
Natural occurrence	primordial
Crystal structure	​face-centered cubic (fcc) (cF4)
Lattice constant	a = 583.57 pm (at triple point: 115.78 K)[7]
Thermal conductivity	9.43×10−3  W/(m⋅K)
Magnetic ordering	diamagnetic[8]
Molar magnetic susceptibility	−28.8×10−6 cm3/mol (298 K)[9]
Speed of sound	(gas, 20 °C) 221 m·s−1 (liquid) 1120 m/s
CAS Number	7439-90-9
History
Discovery and first isolation	William Ramsay and Morris Travers (1898)
Isotopes of krypton v e
Main isotopes[10] Decay abun­dance half-life (t1/2) mode pro­duct 78Kr 0.360% 9.2×1021 y[11] εε 78Se 79Kr synth 35 h ε 79Br β+ 79Br γ – 80Kr 2.29% stable 81Kr trace 2.3×105 y ε 81Br 81mKr synth 13.10 s IT 81Kr ε 81Br 82Kr 11.6% stable 83Kr 11.5% stable 84Kr 57.0% stable 85Kr trace 11 y β− 85Rb 86Kr 17.3% stable
Category: Krypton view talk edit | references

Krypton (from Ancient Greek: κρυπτός, romanized: kryptos 'the hidden one') is a chemical element; it has symbol Kr and atomic number 36. It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps. Krypton is chemically inert.

Krypton, like the other noble gases, is used in lighting and photography. Krypton light has many spectral lines, and krypton plasma is useful in bright, high-powered gas lasers (krypton ion and excimer lasers), each of which resonates and amplifies a single spectral line. Krypton fluoride also makes a useful laser medium. From 1960 to 1983, the official definition of meter was based on the wavelength of one spectral line of krypton-86, because of the high power and relative ease of operation of krypton discharge tubes.