Iron is a chemical element with symbol Fe and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, just ahead of oxygen, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust, being mainly deposited by meteorites in its metallic state, with its ores also being found there.
The mineral pyrite, or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral.
In chemistry, the adjective Ferrous indicates a compound that contains iron(II), meaning iron in its +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to "ferric" or iron(III), meaning iron in its +3 oxidation state, such as the trivalent cation Fe3+. 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 iron(II) oxide for ferrous oxide (FeO), iron(III) oxide for ferric oxide (Fe2O3), and iron(II,III) oxide for the oxide Fe3O4 that contains both forms of iron.
Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare; and iron(II,III) oxide (Fe3O4), which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of iron for the steel industry. Fe2O3 is readily attacked by acids. Iron(III) oxide is often called rust, and to some extent this label is useful, because rust shares several properties and has a similar composition; however, in chemistry, rust is considered an ill-defined material, described as Hydrous ferric oxide.
Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of which is rust.
Iron(II) oxide or ferrous oxide is the inorganic compound with the formula FeO. Its mineral form is known as wüstite. One of several iron oxides, it is a black-colored powder that is sometimes confused with rust, the latter of which consists of hydrated iron(III) oxide. Iron(II) oxide also refers to a family of related non-stoichiometric compounds, which are typically iron deficient with compositions ranging from Fe0.84O to Fe0.95O.
The Burkholderiales are an order of Pseudomonadota. Like all Pseudomonadota, they are Gram-negative. They include several pathogenic bacteria, including species of Burkholderia, Bordetella, and Ralstonia. They also include Oxalobacter and related genera, which are unusual in using oxalic acid as their source of carbon. Other well-studied genera include Alcaligenes, Cupriavidus, Achromobacter, Comamonas, Delftia, Massilia, Duganella, Janthinobacterium, Polynucleobacter, non-pathogenic Paraburkholderia, Caballeronia, Polaromonas, Thiomonas, Collimonas, Hydrogenophaga, Sphaerotilus, Variovorax, Acidovorax, Rubrivivax and Rhodoferax, and Herbaspirillum.
Iron(II,III) oxide is the chemical compound with formula Fe3O4. It occurs in nature as the mineral magnetite. It is one of a number of iron oxides, the others being iron(II) oxide (FeO), which is rare, and iron(III) oxide (Fe2O3) which also occurs naturally as the mineral hematite. It contains both Fe2+ and Fe3+ ions and is sometimes formulated as FeO ∙ Fe2O3. This iron oxide is encountered in the laboratory as a black powder. It exhibits permanent magnetism and is ferrimagnetic, but is sometimes incorrectly described as ferromagnetic. Its most extensive use is as a black pigment. For this purpose, it is synthesized rather than being extracted from the naturally occurring mineral as the particle size and shape can be varied by the method of production.
Ferroglobus is a genus of the Archaeoglobaceae.
Ferroplasma is a genus of Archaea that belong to the family Ferroplasmaceae. Members of the Ferroplasma are typically acidophillic, pleomorphic, irregularly shaped cocci.
Acidovorax facilis is an aerobic, chemoorganotrophic bacterium used as a soil inoculant in agriculture and horticulture.
Iron(III) nitrate, or ferric nitrate, is the name used for a series of inorganic compounds with the formula Fe(NO3)3.(H2O)n. Most common is the nonahydrate Fe(NO3)3.(H2O)9. The hydrates are all pale colored, water-soluble paramagnetic salts.
Acidovorax anthurii is a Gram-negative bacterium which causes plant diseases. This species belongs to Comamonadaceae.
In organometallic chemistry, a metal–ligand multiple bond describes the interaction of certain ligands with a metal with a bond order greater than one. Coordination complexes featuring multiply bonded ligands are of both scholarly and practical interest. Transition metal carbene complexes catalyze the olefin metathesis reaction. Metal oxo intermediates are pervasive in oxidation catalysis.
Mariprofundus ferrooxydans is a neutrophilic, chemolithotrophic, Gram-negative bacterium which can grow by oxidising ferrous to ferric iron. It is one of the few members of the class Zetaproteobacteria in the phylum Pseudomonadota. It is typically found in iron-rich deep sea environments, particularly at hydrothermal vents. M. ferrooxydans characteristically produces stalks of solid iron oxyhydroxides that form into iron mats. Genes that have been proposed to catalyze Fe(II) oxidation in M. ferrooxydans are similar to those involved in known metal redox pathways, and thus it serves as a good candidate for a model iron oxidizing organism.
Halomonas titanicae is a gram-negative, halophilic species of bacteria which was isolated in 2010 from rusticles recovered from the wreck of the RMS Titanic. It has been estimated by Henrietta Mann, one of the researchers that first isolated it, that the action of microbes like Halomonas titanicae may bring about the total deterioration of the Titanic by 2030. While the bacteria have been identified as a potential danger to oil rigs and other man-made objects in the deep sea, they also have the potential to be used in bioremediation to accelerate the decomposition of shipwrecks littering the ocean floor.
Acidovorax radicis is a gram-negative, oxidase-positive, catalase-negative, motile, aerobic bacterium from the family Comamonadaceae which was isolated from the surface of sterilized wheat roots. In opposite to other Acidovorax species it has no phytopathogenic potential, moreover it has been shown that it promote plants growing activity.
Leptothrix cholodnii is a bacterium from the genus Leptothrix, which has the ability to oxidize Fe(II).
Acidithrix ferrooxidans is a heterotrophic, acidophilic and Gram-positive bacterium from the genus Acidithrix. The type strain of this species, A. ferrooxidans Py-F3, was isolated from an acidic stream draining from a copper mine in Wales. This species grows in a variety of acidic environments such as streams, mines or geothermal sites. Mine lakes with a redoxcline support growth with ferrous iron as the electron donor. "A. ferrooxidans" grows rapidly in macroscopic streamer, producing greater cell densities than other streamer-forming microbes. Use in a bioreactors to remediate mine waste has been proposed due to cell densities and rapid oxidation of ferrous iron oxidation in acidic mine drainage. Exopolysaccharide production during metal substrate metabolism, such as iron oxidation helps to prevent cell encrustation by minerals.
Sinirhodobacter ferrireducens is a Gram-negative, facultative anaerobic and Fe(III) oxide-reducing bacterium from the genus Sinirhodobacter.
