Xenon

This week's element is xenon, a noble gas (or inert gas) with the symbol, Xe, and the atomic number, 54. Xenon is a clear and colorless, and odorless gas that is quite heavy. Xenon gas is 4.5 times heavier than Earth's atmosphere (which consists of a mixture of a number of gaseous elements and compounds). This element's mass comes from its nucleus, which contains 54 protons and a varying (but similar) number of neutrons. Xenon has 17 naturally-occurring isotopes (the most for any element), eight of which are stable, the most for any element, except tin , which has ten. Tiny amounts of two xenon isotopes, xenon-133 and xenon-135, leak from nuclear reprocessing and power plants, but are released in higher amounts after a nuclear explosion of accident, such as what occurred at Fukushima. Thus, monitoring xenon's isotopes can ensure compliance with international nuclear test-ban treaties and also to detect whether rogue nations are testing their own nuclear weapons. Xenon was discovered in 1898 in England by the Scottish chemist William Ramsay and English chemist Morris Travers. By examining the spectra emitted by the residue left over after evaporating components of liquid air, they realised they'd discovered another new element. Xenon is rare on Earth, consisting of as little as 1 part in 20 million in Earth's atmosphere. Xenon is used in a number of practical ways. It is probably most familiar because it is used in photographic flash bulbs, in high pressure short-arc lamps for IMAX film projectors (these lamps are explosive, so they require special care when being replaced), and in high pressure arc lamps to produce "safe" ultraviolet light for tanning beds and to sterilise things, such as benchtops in labs. Xenon is also used as a general anaesthetic and in medical imaging. But in my opinion, xenon's most interesting use is as an ion thruster for space travel. NASA designed a Xenon Ion Drive engine that works by firing a beam of high-energy ions at very high speeds and with high efficiency. For example, the Deep Space 1 (DS1) probe shoots out ions at 146, 000 kilometers per hour (more than 88,000 mph). DS1 is probably most memorable for its two flyby encounters with Comet Borrelly in 2001. Several interesting traits of solid xenon appear when it is subjected to pressures equivalent to 1.3 million times Earth's atmospheric pressure; it turns bright blue and takes on the chemical properties of a metal. Xenon is not toxic but many of its compounds are, as the result of their strong oxidizing properties. Waitaminnit , you say. GrrlScientist just said "chemical compounds". Xenon's inert, so what's she on about? It's true: xenon can, under unusual conditions, form compounds with a few other elements. In fact, xenon was the first of the noble gases to form a chemical compound under the guidance and observation of a human. This experiment, originally conceived of by chemist Neil Bartlett and performed in 1962, showed that xenon could be oxidized by another gas, platinum hexa fluoride (Pt F 6 ) to form a solid yellow compound, xenon hexa fluoro platinate. This seminal experiment forever changed how chemists think about the noble gases and launched a new research field in chemistry. Here's our favourite chemistry professor telling us more about Neil Bartlett, about this particular experiment, and about xenon in general: Visit PeriodicVideos 's YouTube channel [ video link ]. .. .. .. .. .. .. .. .. .. .. .. .. 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: Iodine : I , atomic number 53 Tellurium : Te , atomic number 52 Antimony : Sb , atomic number 51 Tin : Sn , atomic number 50 Indium : In , atomic number 49 Cadmium : Cd , atomic number 48 Silver : Ag , atomic number 47 Palladium : Pd , atomic number 46 Rhodium : Rh , atomic number 45 Ruthenium : Ru , atomic number 44 Technetium : Tc , atomic number 43 Molybdenum : Mo , atomic number 42 Niobium : Ni , atomic number 41 Zirconium : Zr , atomic number 40 Yttrium : Y , atomic number 39 Strontium : Sr , atomic number 38 Rubidium : Rr , atomic number 37 Krypton : Kr , atomic number 36 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 the Royal Society of Chemistry's interactive Periodic Table of the Elements that is just really really fun to play with! .. .. .. .. .. .. .. .. .. .. .. .. twitter: @ GrrlScientist facebook: grrlscientist email: [email protected]