Krypton
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.
Gallery
Jurii, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/krypton.php
Emission spectrum
Physical Propertiesmass · density · phase · crystal
Atomic Mass
83.7980Da
Density
0.0034g/L
Phase (STP)
Gas
Melting Point
115.8K
Boiling Point
119.7K
Molar Heat
0.2480J/(mol·K)
Crystal Structure
FCC
Lattice Constant
5.720Å
Atomic Radiiatomic · covalent · van der Waals
Atomic (Empirical)
—
Covalent
117.00pm
Van der Waals
202.00pm
Electronic Propertieselectronegativity · ionization · affinity
Electron Configuration
[Ar] 3d10 4s2 4p6
Electron Shells
2, 8, 18, 8
Electronegativity
—
Electron Affinity
—
1st Ionization Energy
14.0kJ/mol
Oxidation States
0, +2
Orbital DiagramAufbau · Hund's rule · Pauli exclusion
Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6Short: [Ar] 3d10 4s2 4p6
Ionization Energies (36 known)
Emission Spectrumvisible range · characteristic spectral lines
Abundanceby mass
Log scale · ppm = parts per million by mass
Biological Role
Inert noble gas with no biological role.
Discovery
Discovered By
Sir William Ramsey, M.W. Travers
Named By
—
Year
1898
Nuclear Data
Known Isotopes
35
Stable Isotopes
6
Stable Mass Numbers
78, 80, 82, 83, 84, 86
Natural isotopic abundance (IUPAC recommended values)
Isotopes of Kr35 known
| Nuclide | Z | N | Mass (AMU) | Half-life | Decay | Jπ | Abundance |
|---|---|---|---|---|---|---|---|
| 67Kr | 36 | 31 | 66.983305 | 7.40 ms | 2p (0.37%), β⁺ | 3/2- | — |
| 68Kr | 36 | 32 | 67.972489 | 21.6 ms | β⁺, β⁺p (0.9%), p | 0+ | — |
| 69Kr | 36 | 33 | 68.965496 | 27.9 ms | β⁺ (1%), β⁺p (0.94%) | 5/2- | — |
| 78Krstable | 36 | 42 | 77.920366 | Stable | 2β⁺ | 0+ | 35.5000% |
| 80Krstable | 36 | 44 | 79.916378 | Stable | stable (1%) | 0+ | 228.6000% |
| 82Krstable | 36 | 46 | 81.913481 | Stable | stable (1%) | 0+ | 1159.3000% |
| 83Krstable | 36 | 47 | 82.914127 | Stable | stable (1%) | 9/2+ | 1150.0000% |
| 84Krstable | 36 | 48 | 83.911498 | Stable | stable (1%) | 0+ | 5698.7000% |
| 86Krstable | 36 | 50 | 85.910611 | Stable | 2β⁻ | 0+ | 1727.9000% |
| 99Kr | 36 | 63 | 98.958776 | 40.0 ms | β⁻ (1%), β⁻n (0.11%), 2n | 5/2- | — |
| 100Kr | 36 | 64 | 99.962995 | 12.0 ms | β⁻ (1%), β⁻n, 2n | 0+ | — |
| 101Kr | 36 | 65 | 100.969318 | Unknown | β⁻, β⁻n, 2n | 5/2+ | — |