View source for Chemistry:Ferrous

{{Short description|Metal compound containing iron}}
[[File:Iron(II) oxide.jpg|thumb|Ferrous oxide is more correctly called iron(II) oxide.]]

In [[Chemistry:Chemistry|chemistry]], the adjective '''''ferrous''''' indicates a [[Chemistry:Chemical compound|compound]] that contains [[Chemistry:Iron(II)|iron(II)]], meaning [[Chemistry:Iron|iron]] in its +2 [[Chemistry:Oxidation state|oxidation state]], possibly as the [[Chemistry:Valence|divalent]] cation Fe<sup>2+</sup>. It is opposed to ''[[Chemistry:Ferric|ferric]]'', or [[Chemistry:Iron(III)|iron(III)]], meaning iron in its +3 oxidation state, such as the [[Chemistry:Valence|trivalent]] cation Fe<sup>3+</sup>.<ref name=mw>{{cite Merriam-Webster|ferrous |access-date=2008-04-19}}</ref> This usage has been largely replaced by the IUPAC nomenclature, which calls for the oxidation state being indicated by Roman numerals in parentheses, such as [[Chemistry:Iron(II) oxide|iron(II) oxide]] for ferrous oxide (FeO), [[Chemistry:Iron(III) oxide|iron(III) oxide]] for ferric oxide (Fe<sub>2</sub>O<sub>3</sub>), and [[Chemistry:Iron(II,III) oxide|iron(II,III) oxide]] for the oxide {{chem2|Fe3O4}} that contains both forms of iron.

[[File:Pourbaix Diagram of Iron.svg|thumb|[[Chemistry:Pourbaix diagram|Pourbaix diagram]] of aqueous iron]]

Outside chemistry, ''ferrous'' means generally "containing iron".<ref name=mw/> The word is derived from the [[Social:Latin|Latin]] word ''{{lang|la|ferrum}}'' ('iron').<ref>{{Citation | title = Etymology (Meaning of Words) | date = 30 November 2007 | url = http://en.allexperts.com/q/Etymology-Meaning-Words-1474/Origin-word-1.htm | access-date = 19 April 2008 | archive-url = https://web.archive.org/web/20080420180310/http://en.allexperts.com/q/Etymology-Meaning-Words-1474/Origin-word-1.htm | archive-date = 20 April 2008 | url-status = dead }}.</ref> '''Ferrous metals''' include steel and [[Chemistry:Pig iron|pig iron]] (with a carbon content of a few percent) and [[Chemistry:Alloy|alloy]]s of iron with other metals (such as stainless steel).<ref>{{cite web|title=Ferrous Alloys Properties|url=http://www.steelforge.com/literature/ferrousnon-ferrous-materials-textbook/ferrous-metals/|publisher=All Metals & Forge Group|access-date=1 October 2013}}</ref> ''Non-ferrous'' is used to describe [[Chemistry:Metal|metal]]s and alloys that do not contain an appreciable amount of iron.<ref name=mwnon>"[http://www.merriam-webster.com/dictionary/non%20ferrous non-ferrous]" entry in the Merriam-Webster online dictionary.  Accessed on 2008-04-19.</ref>  

The term ''ferrous'' is usually applied only to [[Chemistry:Metal|metal]]s and [[Chemistry:Alloy|alloy]]s.  The adjective ''ferruginous'' is used instead to refer to non-metallic substances that contain iron, such as ''ferruginous water''; or to an orangish-brown color resembling that of [[Chemistry:Rust|rust]].<ref name=mwginous>"[https://www.merriam-webster.com/dictionary/ferruginous ferruginous]" entry in the Merriam-Webster online dictionary.  Accessed on 2019-03-08.</ref>

==Gallery==

{{Gallery
| title        = Ferrous salts
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| File:Eisen(II)-chlorid-Tetrahydrat.jpg
 | alt1= 
 | [[Chemistry:Iron(II) chloride|Ferrous chloride tetrahydrate]], Rokühnite, FeCl<sub>2</sub>·4H<sub>2</sub>O
| File:Iron(II) nitrate hexahydrate.jpg
 | alt2= 
 | [[Chemistry:Iron(II) nitrate|Ferrous nitrate hexahydrate]], Fe(NO<sub>3</sub>)<sub>2</sub>·6H<sub>2</sub>O
| File:Iron(II)-oxalate-sample.jpg
 | alt3=
 | Ferrous oxalate dihydrate, [[Chemistry:Humboldtine|Humboldtine]], FeC<sub>2</sub>O<sub>4</sub>·2H<sub>2</sub>O
| File:7314M-vivianite2.jpg
 | alt4=
 | [[Chemistry:Vivianite|Vivianite]], Ferrous phosphate octahydrate, Fe<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>·8H<sub>2</sub>O
| File:Ferrous_sulfate.jpg
 | alt5=
 | [[Chemistry:Iron(II) sulfate|Ferrous sulfate heptahydrate]], [[Chemistry:Melanterite|Melanterite]], FeSO<sub>4</sub>·7H<sub>2</sub>O
| File:Iron(II)-sulfide-sample.jpg
 | alt6=
 | [[Chemistry:Iron(II) sulfide|Ferrous sulfide]], [[Chemistry:Troilite|Troilite]], FeS
| Iron(II) oxide.jpg
 | Ferrous oxide, [[Chemistry:Wüstite|Wüstite]], FeO
| FeSiO3.png
 | Ferrous silicate, Ferrosilite, FeSiO<sub>3</sub>
}}

==See also==

* {{annotated link|Chemistry:Ferric}} — [ Iron(III)] compounds
* {{annotated link|Physics:Ferromagnetism}}
* {{annotated link|Chemistry:Iron(II) oxide}} (ferrous oxide)
* {{annotated link|Chemistry:Iron(II) bromide}} (ferrous bromide)
* {{annotated link|Engineering:Steelmaking}}

==References==

{{reflist|30em}}

[[Category:Iron]]

{{Sourceattribution|Ferrous}}