Editing Period 6 element (section)

===Lutetium===
{{main|Lutetium}}
'''Lutetium''' ({{IPAc-en|l|juː|ˈ|t|iː|ʃ|i|ə|m}} {{respell|lew|TEE|shee-əm}}) is a [[chemical element]] with the symbol '''Lu''' and [[atomic number]] 71. It is the last element in the [[lanthanide]] series, which, along with the [[lanthanide contraction]], explains several important properties of lutetium, such as it having the highest hardness or density among lanthanides. Unlike other lanthanides, which lie in the [[f-block]] of the [[periodic table]], this element lies in the [[d-block]]; however, [[lanthanum]] is sometimes placed on the d-block lanthanide position. Chemically, lutetium is a typical lanthanide: its only common oxidation state is +3, seen in its oxide, halides and other compounds. In an aqueous solution, like compounds of other late lanthanides, soluble lutetium compounds form a complex with nine water molecules.

Lutetium was independently discovered in 1907 by French scientist [[Georges Urbain]], Austrian mineralogist Baron [[Carl Auer von Welsbach]], and American chemist [[Charles James (chemist)|Charles James]]. All of these men found lutetium as an impurity in the mineral [[ytterbia]], which was previously thought to consist entirely of ytterbium. The dispute on the priority of the discovery occurred shortly after, with Urbain and von Welsbach accusing each other of publishing results influenced by the published research of the other; the naming honor went to Urbain as he published his results earlier. He chose the name lutecium for the new element but in 1949 the spelling of element 71 was changed to lutetium. In 1909, the priority was finally granted to Urbain and his names were adopted as official ones; however, the name cassiopeium (or later cassiopium) for element 71 proposed by von Welsbach was used by many German scientists until the 1950s. Like other lanthanides, lutetium is one of the elements that traditionally were included in the classification "[[rare-earth element|rare earth]]s."

Lutetium is rare and expensive; consequently, it has few specific uses. For example, a [[radioactive isotope]] lutetium-176 is used in [[nuclear technology]] to determine the age of [[meteorite]]s. Lutetium usually occurs in association with the element [[yttrium]] and is sometimes used in metal [[alloy]]s and as a [[catalyst]] in various chemical reactions. <sup>177</sup>Lu-[[DOTA-TATE]] is used for radionuclide therapy (see [[Nuclear medicine]]) on neuroendocrine tumours.
<!------------<ref>{{cite news| url=http://www.iupac.org/reports/provisional/abstract04/connelly_310804.html|title =IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (online draft of an updated version of the "''Red Book''" IR 3-6)| date =2004| accessdate = 2009-06-06}}</ref>----------------->