Editing Metal (section)

===Chemical===
The elements which form metals usually form [[cations]] through electron loss.<ref name="morty"/> Most will react with oxygen in the air to form [[oxide]]s over various timescales ([[potassium]] burns in seconds while iron [[rust]]s over years) which depend upon whether the native oxide forms a [[Passivation (chemistry)|passivation layer]] that acts as a [[diffusion barrier]].<ref>{{Cite book |last1=Bockris |first1=J. O'M |title=Modern electrochemistry. 2 |last2=Reddy |first2=Amulya K. N. |date=1977 |publisher=Plenum Pr |isbn=978-0-306-25002-6 |edition=3. print |location=New York}}</ref><ref>{{Cite book |last1=Kelly |first1=Robert G. |url=https://www.taylorfrancis.com/books/9780203909133 |title=Electrochemical Techniques in Corrosion Science and Engineering |last2=Scully |first2=John R. |last3=Shoesmith |first3=David |last4=Buchheit |first4=Rudolph G. |date=2002-09-13 |publisher=CRC Press |isbn=978-0-203-90913-3 |edition=0 |language=en |doi=10.1201/9780203909133}}</ref> Some others, like [[palladium]], [[platinum]], and [[gold]], do not react with the atmosphere at all; gold can form compounds where it gains an electron (aurides, e.g. [[caesium auride]]). The [[oxide]]s of elemental metals are often [[base (chemistry)|basic]]. However, oxides with very high [[oxidation state]]s such as CrO<sub>3</sub>, Mn<sub>2</sub>O<sub>7</sub>, and OsO<sub>4</sub> often have strictly acidic reactions; and oxides of the less electropositive metals such as BeO, Al<sub>2</sub>O<sub>3</sub>, and PbO, can display both basic and acidic properties. The latter are termed [[amphoteric]] oxides.