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A krypton filled discharge tube shaped like the element’s atomic symbol.
Image: Pslawinski ( Creative Commons Attribution-Share Alike 2.5 Generic license.)
This week's element is Krypton, which has the symbol Kr and the atomic number 36. Krypton is another one of those noble gases, which I often think of as being indifferent gases because as a group, they are unreactive with mostly anything under any but the most extreme of circumstances.
Besides being the name of the fictional home planet of the (also fictional) super-heroes Superman, Supergirl and Krypto the Superdog, Krypton has a few non-fictional uses here on Earth. For example, Krypton-based flash bulbs are used as a source of brilliant white light for high speed photography. Krypton also is mixed with Argon (another noble gas) inside energy-saving fluorescent lamps to reduce their power consumption. A mixture of Krypton and Xenon (yet another noble gas) are used to fill incandescent lamps, allowing higher operating temperatures. Together, these gases create a brighter light results that emits more of the blue portion of the light spectrum than conventional lamps.
Krypton has six stable and naturally-occurring isotopes. Krypton-81, a naturally-occurring radioactive product of atmospheric reactions, has a half-life of 230,000 years. Krypton-81 has been used for dating old (50,000–800,000 years) groundwater. Krypton-83 is used in magnetic resonance imaging (MRI) for imaging airways. Krypton-85 is one of the products of uranium fission and it has a half-life of 10.76 years. The light emitted by the Krypton-86 isotope (wavelength: 605.78 nanometers) was used to define the length of a metre, a standard that was internationally accepted in 1960. Krypton's reign didn't last long, however, and this definition was replaced in late 1983 by a new standard for the metre: the International Bureau of Weights and Measures (Bureau International des Poids et Mesures) defined the meter as the distance that light travels in a vacuum during 1/299,792,458 s.
As our favourite chemistry professor mentions in the embedded video, Krypton is used in the Krypton-Fluoride laser. Besides being a convenient instrument for burning holes in walls, this laser is used for experiments by the nuclear fusion energy research community:
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Video journalist Brady Haran is the man with the camera and the University of Nottingham is the place with the chemists. You can follow Brady on twitter @periodicvideos and the University of Nottingham on twitter @UniNottingham
You've already met these elements:
Bromine: Br, atomic number 35
Selenium: Se, atomic number 34
Arsenic: As, atomic number 33
Germanium: Ge, atomic number 32
Gallium: Ga, atomic number 31
Zinc: Zn, atomic number 30
Copper: Cu, atomic number 29
Nickel: Ni, atomic number 28
Cobalt: Co, atomic number 27
Iron: Fe, atomic number 26
Manganese: Mn, atomic number 25
Chromium: Cr, atomic number 24
Vanadium: V, atomic number 23
Titanium: Ti, atomic number 22
Scandium: Sc, atomic number 21
Calcium: Ca, atomic number 20
Potassium: K, atomic number 19
Argon: Ar, atomic number 18
Chlorine: Cl, atomic number 17
Sulfur: S, atomic number 16
Phosphorus: P, atomic number 15
Silicon: Si, atomic number 14
Aluminium: Al, atomic number 13
Magnesium: Mg, atomic number 12
Sodium: Na, atomic number 11
Neon: Ne, atomic number 10
Fluorine: F, atomic number 9
Oxygen: O, atomic number 8
Nitrogen: N, atomic number 7
Carbon: C, atomic number 6
Boron: B, atomic number 5
Beryllium: Be, atomic number 4
Lithium: Li, atomic number 3
Helium: He, atomic number 2
Hydrogen: H, atomic number 1
Here's a wonderful interactive Periodic Table of the Elements that is just really really fun to play with!
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