| 
| Overview
 |  | Name | Krypton |  | Symbol | Kr |  | Atomic Number | 36 |  | Atomic Weight | 83.798 |  | Density | 3.75 g/l[note] |  | Melting Point | -157.36 °C |  | Boiling Point | -153.22 °C |  | Thermal properties
 |  | Phase | Gas |  | Melting Point | -157.36 °C |  | Boiling Point | -153.22 °C |  | Absolute Melting Point | 115.79 K |  | Absolute Boiling Point | 119.93 K |  | Critical Pressure | 5.5 MPa (54.28 Atm) |  | Critical Temperature | 209.41 K |  | Heat of Fusion | 1.64 kJ/mol |  | Heat of Vaporization | 9.02 kJ/mol |  | Specific Heat | 248.05 J/(kg K)[note] |  | Adiabatic Index | 5/3 |  | Neel Point | N/A |  | Thermal Conductivity | 0.00943 W/(m K) |  | Thermal Expansion | N/A |  | Bulk physical properties
 |  | Density | 3.75 g/l[note] |  | Density (Liquid) | N/A |  | Molar Volume | 0.02235 |  | Brinell Hardness | N/A |  | Mohs Hardness | N/A |  | Vickers Hardness | N/A |  | Bulk Modulus | N/A |  | Shear Modulus | N/A |  | Young Modulus | N/A |  | Poisson Ratio | N/A |  | Refractive Index | 1.000427 |  | Speed of Sound | 1120 m/s |  | Thermal Conductivity | 0.00943 W/(m K) |  | Thermal Expansion | N/A |  | Reactivity
 |  | Valence | 2 |  | Electronegativity | 3 |  | ElectronAffinity | 0 kJ/mol |  | Ionization Energies | | 1350.8, 2350.4, 3565, 5070, 6240, 7570, 10710, 12138, 22274, 25880, 29700, 33800, 37700, 43100, 47500, 52200, 57100, 61800, 75800, 80400, 85300 kJ/mol | 
 |  | Health and Safety
 |  | DOT Hazard Class |  |  | DOT Numbers | 1970 |  | RTECS Number |  |  | NFPA Label | N/A |  | 
| Classifications
 |  | Alternate Names | None |  | Names of Allotropes | None |  | Block | p |  | Group | 18 |  | Period | 4 |  | Series | Noble Gas |  | Electron Configuration | [Ar]4s23d104p6 |  | Color | Colorless |  | Discovery | | 1898 in The  United  Kingdom | 
 |  | Gas phase | Monoatomic |  | CAS Number | CAS7439-90-9 |  | CID Number |  |  | RTECS Number |  |  | Electrical properties
 |  | Electrical Type | N/A |  | Electrical Conductivity | N/A |  | Resistivity | N/A |  | Superconducting Point | N/A |  | Magnetic properties
 |  | Magnetic Type | Diamagnetic |  | Curie Point | N/A |  | Mass Magnetic Susceptibility | -4.4×10-9 m3/Kg |  | Molar Magnetic Susceptibility | -3.69×10-10 m3/mol |  | Volume Magnetic Susceptibility | -1.65×10-8 |  | Abundances
 |  | % in Universe | 4×10-6% |  | % in Sun | N/A |  | % in Meteorites | N/A |  | % in Earth's Crust | 1.5×10-8% |  | % in Oceans | 2.1×10-8% |  | % in Humans | N/A |  | Atomic dimensions and structure
 |  | Atomic Radius | 87 pm |  | Covalent Radius | 116 pm |  | Van der Waals Radius | 202 pm |  | Crystal Structure | Face-centered Cubic |  | Lattice Angles |  |  | Lattice Constants |  |  | Space Group Name | Fm_
3m |  | Space Group Number | 225 |  | Nuclear Properties
 |  | Half-Life | Stable |  | Lifetime | Stable |  | Decay Mode | N/A |  | Quantum Numbers | 1S0 |  | Neutron Cross Section | 25 |  | Neutron Mass Absorption | 0.013 |  | Known Isotopes | | 69Kr, 70Kr, 71Kr, 72Kr, 73Kr, 74Kr, 75Kr, 76Kr, 77Kr, 78Kr, 79Kr, 80Kr, 81Kr, 82Kr, 83Kr, 84Kr, 85Kr, 86Kr, 87Kr, 88Kr, 89Kr, 90Kr, 91Kr, 92Kr, 93Kr, 94Kr, 95Kr, 96Kr, 97Kr, 98Kr, 99Kr, 100Kr | 
 |  | Stable Isotopes |  |  | Isotopic Abundances |  |  |