Editing Period 6 element (section)

===Platinum===
{{main|Platinum}}
'''Platinum''' is a [[chemical element]] with the [[chemical symbol]] '''Pt''' and an [[atomic number]] of 78.

Its name is derived from the Spanish term ''platina'', which is literally translated into "little silver".<ref>[http://www.britannica.com/EBchecked/topic/464081/platinum-Pt "platinum (Pt)."] Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2012. Web. 24 April 2012</ref><ref>{{OEtymD|platinum}}</ref><!--source for "platina del Pinto"<ref>{{cite book|last=Woods|first=Ian|title=The Elements: Platinum|publisher=Benchmark Books|year=2004|series=The Elements|isbn=978-0-7614-1550-3}}</ref>--> It is a [[density|dense]], [[malleability|malleable]], [[ductility|ductile]], [[precious metal|precious]], gray-white [[transition metal]].

Platinum has six naturally occurring [[isotopes of platinum|isotopes]]. It is one of the [[Abundance of elements in Earth's crust|rarest elements in the Earth's crust]] and has an average abundance of approximately 5&nbsp;μg/kg. It is the [[Reactivity series|least reactive metal]]. It occurs in some [[nickel]] and [[copper]] ores along with some native deposits, mostly in South Africa, which accounts for 80% of the world production.

As a member of the [[platinum group]] of elements, as well as of the [[group 10 element|group 10]] of the [[periodic table of elements]], platinum is generally non-reactive. It exhibits a remarkable resistance to corrosion, even at high temperatures, and as such is considered a [[noble metal]]. As a result, platinum is often found chemically uncombined as native platinum. Because it occurs naturally in the [[alluvium|alluvial sands]] of various rivers, it was first used by [[pre-Columbian]] South American natives to produce artifacts. It was referenced in European writings as early as 16th century, but it was not until [[Antonio de Ulloa]] published a report on a new metal of [[Colombia]]n origin in 1748 that it became investigated by scientists.

Platinum is used in [[catalytic converter]]s, laboratory equipment, [[electrical contacts]] and [[electrode]]s, [[platinum-resistance thermometer]]s, [[dentistry]] equipment, and jewelry. Because only a few hundred tonnes are produced annually, it is a scarce material, and is highly valuable. Being a [[heavy metals|heavy metal]], it leads to health issues upon exposure to its salts, but due to its corrosion resistance, it is not as toxic as some metals.<ref>{{cite web|url= http://www.euro.who.int/__data/assets/pdf_file/0015/123081/AQG2ndEd_6_11Platinum.PDF|title= Platinum&#124;|access-date= 2012-08-28|archive-date= 2012-10-18|archive-url= https://web.archive.org/web/20121018173735/http://www.euro.who.int/__data/assets/pdf_file/0015/123081/AQG2ndEd_6_11Platinum.PDF|url-status= dead}}</ref> Its compounds, most notably [[cisplatin]], are applied in [[chemotherapy]] against certain types of cancer.<ref>{{cite journal | pmid = 20593091 | year = 2010 | last1 = Wheate | first1 = N. J. | last2 = Walker | first2 = S. | last3 = Craig | first3 = G. E. | last4 = Oun | first4 = R. | title = The status of platinum anticancer drugs in the clinic and in clinical trials | volume = 39 | issue = 35 | pages = 8113–27 | doi = 10.1039/C0DT00292E | journal = Dalton Transactions| url = https://ses.library.usyd.edu.au/bitstream/2123/9269/2/41%20Dalton%20perspective.pdf | hdl = 2123/14271 | hdl-access = free }}</ref>