Editing Period 6 element (section)

===Bismuth===
{{main|Bismuth}}
'''Bismuth''' is a [[chemical element]] with symbol '''Bi''' and [[atomic number]] 83. Bismuth, a trivalent [[other metal]], chemically resembles [[arsenic]] and [[antimony]]. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The [[free element]] is 86% as dense as [[lead]]. It is a brittle metal with a silvery white color when newly made, but often seen in air with a pink tinge owing to the surface oxide. Bismuth metal has been known from ancient times, although until the 18th century it was often confused with lead and tin, which each have some of bismuth's bulk physical properties. The etymology is uncertain but possibly comes from Arabic {{Transliteration|ar|bi ismid}} meaning having the properties of antimony<ref>[http://webmineral.com/data/Bismuth.shtml Bismuth]. Web Mineral. Retrieved on 2011-12-17.</ref> or German words {{lang|de|weisse masse}} or {{lang|de|wismuth}}  meaning "white mass".<ref name="arizona1">{{cite book|editor1=Anthony, John W. |editor2=Bideaux, Richard A. |editor3=Bladh, Kenneth W. |editor4=Nichols, Monte C. |title=Handbook of Mineralogy|publisher=Mineralogical Society of America |place=Chantilly, VA, US |volume=I (Elements, Sulfides, Sulfosalts) |chapter-url=http://rruff.geo.arizona.edu/doclib/hom/bismuth.pdf|chapter=Bismuth |date=1990 |access-date=December 5, 2011 |isbn=978-0-9622097-0-3 }}</ref>

Bismuth is the most naturally [[Diamagnetism|diamagnetic]] of all metals, and only [[mercury (element)|mercury]] has a lower [[thermal conductivity]].

Bismuth has classically been considered to be the heaviest naturally occurring stable element, in terms of atomic mass. Recently, however, it has been found to be very slightly radioactive: its only primordial isotope [[bismuth-209]] decays via [[alpha decay]] into [[thallium-205]] with a [[half-life]] of more than a [[1000000000 (number)|billion]] times the estimated [[age of the universe]].<ref>{{cite news| url=http://physicsweb.org/articles/news/7/4/16| title=Bismuth breaks half-life record for alpha decay| date=2003-04-23| publisher=Physicsweb| first=Belle| last= Dumé}}</ref>

Bismuth compounds (accounting for about half the production of bismuth) are used in [[cosmetics]], pigments, and a few pharmaceuticals. Bismuth has unusually low [[toxicity]] for a heavy metal. As the toxicity of [[lead]] has become more apparent in recent years, alloy uses for bismuth metal (presently about a third of bismuth production), as a replacement for lead, have become an increasing part of bismuth's commercial importance.