Krypton

Krypton (Kr)

Colorless gaseous element, belongs to the noble gases. Occurs in the air, 0.0001% by volume. It can be extracted from liquid air by fractional distillation. Generally not isolated, but used with other inert gases in fluorescent lamps. Five natural isotopes, and five radioactive isotopes. Kr-85, the most stable radioactive isotope, has a half-life of 10.76 years and is produced in fission reactors. Practically inert, though known to form compounds with Fluorine.
Atomic Number36
Atomic Weight83.798
Mass Number84
Group18
Period4
Blockp
Protons36 p+
Neutrons48 n0
Electrons36 e-
Krypton discharge tube.jpg Animated Bohr Model Enhanced Bohr Model Bohr Model Orbital Diagram

Properties

Atomic Radius
Atomic Volume
Covalent Radius
117 pm
Metallic Radius
Ionic Radius
Crystal Radius
Van der Waals radius
202 pm
Density
0.003425 g/cm³
Boiling Point
120.85 K
Melting Point
116.6 K
Electrons per shell2, 8, 18, 8
Electronegativity
Electrophilicity
Proton Affinity
424.6 kJ/mol
Electron Affinity
Ionization Potential
13.9996049 eV/particle
Heat of Vaporization
9.05 kJ/mol
Heat of Fusion
Heat of Formation
Molar Heat Capacity
20.786 J/(mol K)
Specific Heat Capacity
0.248 J/(g⋅K)
Thermal Conductivity
0.0095 W/(m K)
Gas Basicity
402.4 kJ/mol
Dipole Polarizability
16.78 a₀
C6 Dispersion Coefficient
130 a₀
Oxidation States2
Color
Colorless
Crystal StructureFace Centered Cubic (FCC)
Lattice Constant
5.72 Å
Bulk Modulus
Electrical Resistivity
Electron Configuration[Ar] 3d10 4s2 4p6
Magnetic Ordering
Magnetic Susceptibility
PhaseGas
Poisson Ratio
Shear Modulus
Young's Modulus
Allotropes
Alternate Names
Adiabatic Index
Appearance
Electric Conductivity
Critical Pressure
Critical Temperature
Curie Point
Electrical
Hardness
Magnetic Susceptibility
Magnetic
Neel Point
Neutron Cross Section
Neutron Mass Absorption
Gas Phase
Quantum Numbers
Refractive Index
Space Group
Speed of Sound
Superconducting Point
Thermal Expansion
Valence Electrons
Classification
CategoryNoble gases, Noble gases
CAS GroupVIII
IUPAC GroupVIIIA
Glawe Number4
Mendeleev Number115
Pettifor Number4
Geochemical Classvolatile
Goldschmidt Classatmophile
Radioactivity
RadioactiveNo
Decay Mode
Half-Life
Lifetime
Abundance
Abundance in Earth's crust
0.0001 mg/kg
Abundance in Oceans
0.00021 mg/L
Abundance in Human Body
Abundance in Meteor
Abundance in Sun
Abundance in Universe4×10-6%

Isotopes of Krypton

Stable Isotopes
78Kr 80Kr 82Kr 83Kr 84Kr 86Kr
Unstable Isotopes
69Kr 70Kr 71Kr 72Kr 73Kr 74Kr 75Kr 76Kr 77Kr 79Kr 81Kr 85Kr 87Kr 88Kr 89Kr 90Kr 91Kr 92Kr 93Kr 94Kr 95Kr 96Kr 97Kr 98Kr 99Kr 100Kr

History

Scottish chemist Sir William Ramsay and his assistant English chemist Morris Travers discovered krypton in 1898 in London. They found krypton in the residue left from evaporating nearly all components of liquid air. William Ramsay was awarded the 1904 Nobel Prize in Chemistry for discovery of a series of noble gases, including krypton. From the Greek word kryptos, hidden

DiscoverersSir William Ramsey, M.W. Travers
Discovery LocationGreat Britain
Discovery Year1898
Name OriginGreek: kryptos (hidden).
Krypton is considered to be non-toxic
When ionized, krypton gas emits bright white light

Uses

Krypton is used in certain photographic flash lamps for high-speed photography. Krypton-83 has application in magnetic resonance imaging (MRI) for imaging airways. Krypton is used as a filling gas for energy-saving fluorescent lights and as an inert filling gas in incandescent bulbs. Used in lighting products. Some is used as inert filler-gas in incandescent bulbs. Some is mixed with argon in fluorescent lamps. The most important use is in flashing stroboscopic lamps that outline airport runways.

Sources

Forms 1 millionth of the atmosphere. Obtained from production of liquid air.