Samarium

This week, we meet samarium, which has the atomic number 62 and the symbol Sm (although Sa was also widely used until the 1920s). This element, which is not found in its elemental form in nature, was named after the mineral, samarskite, from which it was first extracted in 1879. Samarium is a common element, being the 40th most common on earth and thus, hardly deserving of its name, "rare earth metal". Samarium is moderately hard and is a lustrous silver colour. It easily and rapidly ox idizes in air -- and even under mineral oil! -- so it must be stored under argon or another noble gas. Like many elements, samarium is fun because its various oxidation states have a particular colour. For example, Sm +2 is blood-red whilst Sm +3 is pale green. Samarium has no identifiable role in the body, nor is it toxic or poisonous, so it's rather boring for the biologists in the crowd! However, that said, samarium does make a rather wonderful magnet when combined with cobalt as either Sm Co 5 or Sm 2 Co 17 . Samarium- cobalt magnets are quite brittle so they are often covered with a protective layer of nickel . Samarium- cobalt magnets are 2-3 times more expensive than neodymium magnets and nearly as strong as neodymium magnets. However, unlike neodymium magnets, which work best at temperatures lower than 150 o C, samarium- cobalt magnets work best at high temperatures (270 o C or higher). Currently, a samarium- cobalt magnet is being developed for use in firefighters' uniforms. Samarium has a few other uses; samarium ox ide, Sm 2 O 3 , is added to glass to absorb infrared radiation, it is one of the elements used to make the carbon arc lights that the motion picture industry uses for studio and projector lighting, and samarium is also present in tiny amounts in Misch metal, which are used as flints for lighters. Samarium is also used in electric guitars pickups, iPods and headphones. According to one of my sources, samarium has a peculiar property: when the surface of its black-coloured sulf ide (Sm S ) crystals are scratched, they transform into gold-coloured crystals that conduct like a metal (doi: 10.1134/S1063785009110030 ). Here's two of our favourite chemists telling us more about the wonders of samarium: [ 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 @ UniofNottingham You've already met these elements: Promethium : Pm , atomic number 61 Neodymium : Nd , atomic number 60 Praseodymium : Pr , atomic number 59 Cerium : Ce , atomic number 58 Lanthanum : La , atomic number 57 Barium : Ba , atomic number 56 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 Pinterest: grrlscientist email: [email protected]