Iron oxide formula

What is the Iron oxide formula: Let us know about the Iron Oxide formula. An iron oxide is any compound between iron and oxygen. They are characterized by being ionic and crystalline, and they are scattered products of the degradation of their minerals, composing floors, vegetation masses and even the interior of living organisms.

Iron oxide formula

It is then one of a family of compounds that predominate in the Earth’s crust. What are they really? Sixteen iron oxides are known to date, most of them of natural origin and others synthesized under extreme conditions of pressure or temperature.

A portion of ferric oxide powder is shown in the upper image. Its characteristic red color is characterized by the iron covering of many architectural elements known as rust. In addition, it is found on slopes, mountains or soils, mixed with other minerals, such as the yellow powder of goethite (α-FeOOH).

The most commonly known iron oxides are hematite (α-Fe 2 O 3 ) and magmite ((- Astha) 2 O 3 ), both polymorphisms of ferric oxide; And at least, magnetite (believe 3 O 4 ). Their multicolored structures and their large surface area make them interesting materials such as sorbents, or for the synthesis of nanoparticles with wide applications.


Iron oxide formula

The upper image represents the crystalline structure of FeO, one of the iron oxides where the valence of iron is +2. The red spheres correspond to the ions O 2- , while the yellow ones for Fe 2+ . Note also that each of the 2+ confidences is surrounded by six O 2- , forming an octahedral coordination unit.

Therefore, the structure of FeO can be “crumbled” into units of FeO 6 , where the central atom is confidently 2+ . In the case of oxyhydroxide or hydroxide, the octahedral unit is FeO 3 (OH) 3 .

Instead of octahedrons, some structures have tetrahedral units, FeO 4 . For this reason the structures of iron oxides are usually represented with octahedrons or tetrahedra with iron centers.

The composition of iron oxides depends on pressure or temperature, the Fe/O ratio (i.e., how many oxygens are in per iron and vice versa), and the valency of iron (+2, +3 and, very rarely) in synthetic oxides. ever, +4).

In general, the heavy ions O 2- are the sheet-formers whose holes house the Fe cations 2+ O believe 3+ . Thus, there are oxides (such as magnetite) that have irons with both valences.


Iron oxides present polymorphism, that is, different structures or crystal arrangements for the same compound. Ferric oxide, Fe 2 O 3 , has four possible polymorphs. Hematite, α-Fe 2 O 3 , it is the most stable; This is followed by magmite, ite -fa 2 O 3 , and synthetic for-Fe 2 O 3 and ith -fa 2 O 3 .

They all have their own types of structures and crystalline systems. However, the 2 : 3 ratio remains constant, so there are three ions O 2 – 3+ for every two cations . The difference is how the octagonal FeO units are located 6 in space and how you are together.

structural link

Octahedral FeO units 6 They can be seen with the help of a better image. O, the corners of the octahedron are 2- , while the center of it has confidence 2+ O confidence 3+ (for the case of confidence 2 O 3 ). The way these octahedra are arranged in space reveals the structure of the oxide.

However, they also affect how they are connected. For example, two octahedrons can be joined by touching their two ends, represented by an oxygen bridge: Fe–O–Fe. Similarly, octahedra can be connected through their edges (adjacent to each other). This would then be represented with two oxygen bridges: Fe- (O) 2 -reactivity.

And finally, octahedra can interact through their faces. Thus, the representation would now be with three oxygen bridges: Fe- (O) 3 -Fe. The way the octahedrons are connected will vary the interatomic Fe–Fe distance and, therefore, the physical properties of the oxide.


An iron oxide is a compound with magnetic properties. These antagonists can be ferro or ferrimagnetic, and depend on the validity of Fe and how the cations in the solid interact.

Because the structures of solids are so diverse, so are their physical and chemical properties.

For example, the polymorphs of Fe and the hydrates 2 O 3 have different melting points (which range between 1200 and 1600 C) and densities. However, they are common in low solubility due to Fe 3+ , have the same molecular mass, are brown in color and dissolve sparingly in acid solutions.


IUPAC establishes three ways to name an iron oxide. All three are very useful, although for complex oxides (such as Fe 7 O 9 ) their simplicity rules over the others.

systematic nomenclature

The numbers of oxygen and iron are taken into account, they are named with the Greek numeral prefix mono-, di-, tri-, etc. According to this nomenclature Astha 2 O 3 It is called: Oxide of tri di iron. And 7 O 9 for the sake of faith its name would be: Non-Toxic HeptaHiyaro.

stock nomenclature

It considers the valency of iron. If it is about the belief 2+ , iron oxide is written … and its validity with Roman numerals enclosed in parentheses. Faith for 2 O 3 Its name is: Iron Oxide (III).

Note that the confidence 3+ can be determined by algebraic sums. If o2- has two negative charges, and there are three of them, add-6. We need +6 to neutralize this -6, but there are two Fe, so they have to be divided by two, +6/2 + +:

2X (metal valence) + 3 (-2) = 0

Simply cleaning up X gives you the valence of Fe in the oxide. But if X is not a whole number (as with almost all other oxides), then Fe is a mixture of 2+ and Belief 3+ .

traditional nomenclature

The suffix -ico is given for the prefix ferr- when Fe has a valence of +3, and which occurs when its valence is 2+. Thus, trust 2 O 3 It is called: ferric oxide.



Iron oxides have an extremely high crystallization energy, which allows the formation of very small crystals, but with a large surface area.

For this reason they are of great interest in the field of nanotechnology, where they design and synthesize oxide nanoparticles (NPs) for specific purposes:

– as a catalyst.

as a storehouse of drugs or genes within the body

In the design of sensory surfaces for a variety of biomolecules: proteins, sugars, fats

To store magnetic data


Because some oxides are very stable, they serve to dye textiles or give bright colors to the surfaces of any material. from mosaics of floors; red, yellow and orange colors (even green); Ceramics, plastics, leather, and even architectural works.

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