Platinum
Chemical
### Chemical

[thumb\| upright\=1\.3\|left\|Platinum being dissolved in hot *[aqua regia](/wiki/Aqua_regia "Aqua regia")*](/wiki/File:Platin_l%C3%B6st_sich_in_hei%C3%9Fem_K%C3%B6nigswasser.jpg "Platin löst sich in heißem Königswasser.jpg")

Platinum has excellent resistance to [corrosion](/wiki/Corrosion "Corrosion"). Bulk platinum does not oxidize in air at any temperature, but it forms a thin surface film of [](/wiki/Platinum_dioxide "Platinum dioxide") that can be easily removed by heating to about 400 °C.

The most common [oxidation states](/wiki/Oxidation_state "Oxidation state") of platinum are \+2 and \+4\. The \+1 and \+3 oxidation states are less common, and are often stabilized by metal bonding in bimetallic (or polymetallic) species. Tetracoordinate platinum(II) compounds tend to adopt 16\-electron [square planar](/wiki/Square_planar "Square planar") geometries. Although elemental platinum is generally unreactive, it is attacked by [chlorine](/wiki/Chlorine "Chlorine"), [bromine](/wiki/Bromine "Bromine"), [iodine](/wiki/Iodine "Iodine"), and [sulfur](/wiki/Sulfur "Sulfur"). It reacts vigorously with fluorine at  to form [platinum tetrafluoride](/wiki/Platinum_tetrafluoride "Platinum tetrafluoride"). Platinum is insoluble in [hydrochloric](/wiki/Hydrochloric_acid "Hydrochloric acid") and [nitric acid](/wiki/Nitric_acid "Nitric acid"), but dissolves in hot *[aqua regia](/wiki/Aqua_regia "Aqua regia")* (a mixture of nitric and hydrochloric acids), to form aqueous [chloroplatinic acid](/wiki/Chloroplatinic_acid "Chloroplatinic acid"), :

 
As a [soft acid](/wiki/HSAB_theory "HSAB theory"), the  ion has a great affinity for sulfide and sulfur ligands. Numerous DMSO complexes have been reported and care is taken in the choosing of reaction solvents.

In 2007, the German scientist [Gerhard Ertl](/wiki/Gerhard_Ertl "Gerhard Ertl") won the [Nobel Prize in Chemistry](/wiki/Nobel_Prize_in_Chemistry "Nobel Prize in Chemistry") for determining the detailed molecular mechanisms of the catalytic oxidation of [carbon monoxide](/wiki/Carbon_monoxide "Carbon monoxide") over platinum ([catalytic converter](/wiki/Catalytic_converter "Catalytic converter")).


How does platinum's resistance to corrosion compare to other metals?