Chemical & Physical Properties
Atomic Number: 36
Atomic Weight: 83.80
Discovery: Sir William Ramsey, M.W. Travers, 1898 (Great Britain)
Electron Configuration: [Ar] 4s2 3d10 4p6
Word Origin: Greek kryptos: hidden
Isotopes: There are 30 known isotopes of krypton ranging from Kr-69 to Kr-100. There are 6 stable isotopes: Kr-78 (0.35% abundance), Kr-80 (2.28% abundance), Kr-82 (11.58% abundance), Kr-83 (11.49% abundance), Kr-84 (57.00% abundance), and Kr-86 (17.30% abundance).
Element Classification: Inert Gas
Density: 3.09 g/cm3 (@4K - solid phase)
2.155 g/mL (@-153°C - liquid phase)
3.425 g/L (@25°C and 1 atm - gas phase)
Melting Point (K): 116.6
Boiling Point (K): 120.85
Appearance: dense, colorless, odorless, tasteless gas
Atomic Volume (cc/mol): 32.2
Covalent Radius (pm): 112
Specific Heat (@20°C J/g mol): 0.247
Evaporation Heat (kJ/mol): 9.05
Pauling Negativity Number: 0.0
First Ionizing Energy (kJ/mol): 1350.0
Oxidation States:0, 2
Lattice Structure: Face-Centered Cubic
Lattice Constant (Å): 5.720
CAS Registry Number: 7439-90-9
- Sir William Ramsay was awarded the 1904 Nobel Prize in Chemistry for the discovery of the noble gasses, including Krypton.
- The meter was defined in 1960 as 1,650,763.73 wavelengths of the 605.78 nanometer spectral line from Krypton-86. This standard was replaced in 1983.
- Krypton is usually inert, but it can form molecules. The first krypton molecule, krypton difluoride (KrF2), was discovered in 1963.
- Earth's atmosphere has approximately 1 part per million abundance of krypton.
- Krypton can be obtained by fractional distillation from air.
- Light bulbs containing krypton gas can produce a bright white light useful for photography and runway lights.
- Krypton is often used in gas and gas ion lasers.