Barium

This week's element is barium, which has the symbol, Ba, and the atomic number, 56. Barium's name comes from the Greek word for "heavy", because some barium-containing ores are very dense. Interestingly, barium metal is unexpectedly light, having roughly half the density of iron. Pure barium is a soft lustrous silver-coloured alkaline earth metal, but you'll never see it in its pure state in the wild because barium reacts strongly with air, particularly oxygen , forming a number of compounds in the process. Elemental barium is so attracted to oxygen that its primary industrial use is to scavenge the last traces of oxygen and other gases from electronic vacuum tubes such as television cathode ray tubes. If you were a witch or an alchemist living in the Middle Ages, you would be quite familiar with several of the interesting qualities of certain barium-containing minerals. For example, near Bologna, Italy, there is a deposit of smooth rounded barite stones. Known as "Bologna stones", they glow for years after being exposed to light. Most people see one of barium's more appealing qualities several times per year, although they are probably unaware of this. Several green fireworks colours are provided by salts containing barium; Barium nitr ate creates a yellow green and brilliant green is created by barium mono chloride . When ingested, most barium salts react strongly with stomach acids producing deadly results. For example, barium carbon ate is a common rat poison that can kill within ten minutes. Barium acts by blocking potassium ion channels, which affects the nervous system, causing tremors and paralysis followed by death from cardiac failure. This quality was the basis for a famous murder when 16-year-old Texan Marie Robards stole another barium salt, barium acetate, from her school chemistry lab and surreptitiously added it to a meal of refried beans she prepared for her father in 1993 [ PDF ]. It would have been a "perfect murder" if she had not confessed to a classmate. Ms Robards apparently got the idea from Shakespeare's classic play, Hamlet . But barium is probably most familiar to most people today because it is the key component of barium enemas and barium meals used in medicine, as their names imply. Unlike many barium salts, barium sulf ate, Ba S O 4 , is chemically inert and therefore, is safe to ingest. When x-rayed, it produces a beautiful image of the gastrointestinal tract because it absorbs x-rays whilst the surrounding tissue allows x-rays to pass through unimpeded. This is the basis of a common medical test used to diagnose GI-tract issues. Trivia buffs and rock hounds will appreciate this little known fact about the lovely barium-containing mineral, benitoite, that I've featured as the above-the-jump image. A beautiful blue colour under ambient light, this rare barium titanium silic ate crystal fluoresces blue under short-wave UV light. But if you run across the even rarer white or clear and colourless benitoite crystals, they fluoresce red under long-wave UV light. So far, gemstone-quality benitoite crystals have only been found in California, which has adopted this mineral as its official state gem. Here's our favourite chemistry professor and his colleagues telling us more about the wonders of barium: [ 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: Cæsium : Cs , atomic number 55 Xenon : Xe , atomic number 54 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]