Facts About the Element Krypton

Krypton Basic Facts

• Atomic Number: 36
• Symbol: Kr
• 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)

Krypton Physical Data

• 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

Trivia

• 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.

Sources:

• Los Alamos National Laboratory (2001)
• Crescent Chemical Company (2001)
• Lange's Handbook of Chemistry (1952)
• CRC Handbook of Chemistry & Physics (18th Ed.) International Atomic Energy Agency ENSDF database (Oct 2010)