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oxide

  (ŏk'sīd') pronunciation
n.

A binary compound of an element or radical with oxygen.

[French : ox(ygène), oxygen; see oxygen + (ac)ide, acid (from Latin acidus, tart, acid; see acid).]

oxidic ox·id'ic (ŏk-sĭd'ĭk) adj.
 
 

A binary compound of oxygen with another element. Oxides have been prepared for essentially all the elements except the noble gases. Often, several different oxides of a given element can be prepared; a number exist naturally in the Earth's crust and atmosphere: silicon dioxide (SiO2) in quartz; aluminum oxide (A12O3) in corundum; iron oxide (Fe2O3) in hematite; carbon dioxide (CO2) gas; and water (H2O).

Most elements will react with oxygen at appropriate temperature and oxygen pressure conditions, and many oxides may thus be directly prepared. Most metals in massive form react with oxygen only slowly at room temperatures because the first thin oxide coat formed protects the metal. The oxides of the alkali and alkaline-earth metals, except for beryllium and magnesium, are porous when formed on the metal surface, and they provide only limited protection to the continuation of oxidation, even at room temperatures. Gold is exceptional in its resistance to oxygen, and its oxide (Au2O3) must be prepared by indirect means. The other noble metals, although ordinarily resistant to oxygen, will react at high temperatures to form gaseous oxides.

Oxides may be classified as acidic or basic according to the character of the solution resulting from their reactions with water. The nonmetal oxides generally form acid solutions and the metal oxides generally form alkaline solutions. See also Acid and base; Equivalent weight; Oxygen.


 

n

A compound of oxygen with another element or radical such as iron.

 

Any of a large and important class of chemical compounds in which oxygen is combined with another element. Metal oxides contain a metal cation and the oxide anion (O2-); they typically react with water to form bases or with acids to form salts. Oxides of nonmetallic elements are volatile compounds in which a covalent bond joins the oxygen and the nonmetal; they react with water to form acids or with bases to form salts. A few substances (e.g., aluminum, zinc) form amphoteric oxides, which form salts with both acids and bases. Certain organic compounds form oxides in which the oxygen is covalently bonded to an atom of nitrogen (amine oxides), phosphorus (phosphine oxides), or sulfur (sulfoxides) in the organic molecule.

For more information on oxide, visit Britannica.com.

 
chemical compound containing oxygen and one other chemical element. Oxides are widely and abundantly distributed in nature. Water is the oxide of hydrogen. Silicon dioxide is the major component of sand and quartz. Carbon dioxide is given off during respiration by animals and plants. Carbon monoxide, sulfur dioxide, and oxides of nitrogen are among the waste gases of gasoline-burning internal-combustion engines. Nitrous oxide is an oxide of nitrogen often called laughing gas. Many of the metals form oxides. Some metal oxides, e.g., those of iron, aluminum, tin, and zinc, are important as ores. Litharge and red lead are lead oxides used as pigments in paint. A number of elements, e.g., arsenic, carbon, manganese, nitrogen, phosphorous, and sulfur, combine with oxygen to form more than one oxide. The inert gases do not form oxides. The halogens and inactive metals do not combine directly with oxygen, but their oxides can be formed by indirect methods. Oxides are usually named according to the number of oxygen atoms present in a molecule, e.g., monoxide (or simply oxide), dioxide, trioxide. In a molecule of carbon monoxide, CO, for example, there is one oxygen atom; in carbon dioxide, CO2, there are two; and in phosphorus pentoxide, P2O5, there are five. Oxides are commonly classified as acidic or basic oxides or anhydrides. Sulfur trioxide is an acid anhydride; it reacts with water to form sulfuric acid. Phosphorus pentoxide reacts vigorously with water to form phosphoric acid. Many metal oxides react with water to form alkaline hydroxides, e.g., calcium oxide (lime) reacts with water to form calcium hydroxide (slaked lime). Some metal oxides do not react with water but are basic in that they react with an acid to form a salt and water. Others exhibit amphoterism; i.e., they react with both acids and bases. Still others are neutral and nonreactive.


 

A compound of oxygen with an element or radical.

 
Wikipedia: oxide

An oxide is a chemical compound containing at least one oxygen atom and other elements. Most of the earth's crust consists of oxides. Oxides result when elements are oxidized by air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon monoxide and carbon dioxide. Even materials that are considered to be pure elements often contain a coating of oxides. For example, aluminium foil has a thin skin of Al2O3 that protects the foil from further corrosion.

Most oxides are insoluble in water

The oxide ion, O2−, is the conjugate base of the hydroxide ion, OH, and is encountered in ionic solid such as calcium oxide. O2− is unstable in aqueous solution − its affinity for H+ is so great (pKb ~ -22) that it abstracts a proton from a solvent H2O molecule:

O2− + H2O → 2 OH

Although many anions are stable in aqueous solution, ionic oxides are not. For example, sodium chloride dissolves readily in water to give a solution containing the constituent ions, Na+ and Cl-. Oxides do not behave like this. If an ionic oxide dissolves, the O2− ions become protonated. Although Calcium oxide, CaO, is said to "dissolve" in water, the products include hydroxide:

CaO + H2O → Ca2+ + 2 OH-

In fact, no monoatomic dianion is known to dissolve in water - all are so basic that they undergo hydrolysis. Concentrations of oxide ion in water are too low to be detectable with current technology.

Authentic soluble oxides do exist of course, but they release oxyanions, not O2-. Well known soluble salts of oxyanions include sodium sulfate (Na2SO4), potassium permanganate (KMnO4), and sodium nitrate (NaNO3).

Nomenclature

In the 18th century, oxides were named calxes or calces after the calcination process used to produce oxides. Calx was later replaced by oxyd.

Oxides are usually named after the number of oxygen atoms in the oxide. Oxides containing only one oxygen are called oxides or monoxides, those containing two oxygen atoms are dioxides, three oxygen atoms makes it a trioxide, four oxygen atoms are tetroxides, and so on following the Greek numerical prefixes.

Two other types of oxide are peroxide, O22−, and superoxide, O2. In such species, oxygen is assigned higher oxidation states than oxide.

Types of oxides

Oxides of more electropositive elements tend to be basic. They are called basic anhydrides; adding water, they may form basic hydroxides. For example, sodium oxide is basic; when hydrated, it forms sodium hydroxide.

Oxides of more electronegative elements tend to be acidic. They are called acid anhydrides; adding water, they form oxoacids. For example, dichlorine heptoxide is acid; perchloric acid is a more hydrated form.

Some oxides can act as both acid and base at different times. They are amphoteric. An example is aluminium oxide. Some oxides do not show behavior as either acid or base.

The oxides of the chemical elements in their highest oxidation state are predictable and the chemical formula can be derived from the number of valence electrons for that element. Even the chemical formula of O4, tetraoxygen, is predictable as a group 16 element. One exception is copper for which the highest oxidation state oxide is copper(II) oxide and not copper(I) oxide. Another exception is fluoride that does not exist as expected as F2O7 but as OF2 with the least electronegative element given priority. [1]. Phosphorus pentoxide, the third exception is not properly represented by the chemical formula P2O5 but by P4O10

Common oxides sorted by oxidation state

See also

  • See Category:Oxides for a list of oxides.

References

  1. ^ Fully Exploiting the Potential of the Periodic Table through Pattern Recognition Schultz, Emeric. J. Chem. Educ. 2005 82 1649.

 
Translations: Translations for: Oxide

Dansk (Danish)
n. - oksyd, oxid

Nederlands (Dutch)
zuurstofverbinding

Français (French)
n. - oxyde

Deutsch (German)
n. - (Chem.) Oxyd

Ελληνική (Greek)
n. - (χημ.) οξείδιο

Italiano (Italian)
ossido

Português (Portuguese)
n. - óxido (m)

Русский (Russian)
окись, окисел

Español (Spanish)
n. - óxido

Svenska (Swedish)
n. - oxid

中文(简体) (Chinese (Simplified))
氧化物

中文(繁體) (Chinese (Traditional))
n. - 氧化物

한국어 (Korean)
n. - 산화물

日本語 (Japanese)
n. - 酸化物

العربيه (Arabic)
‏(الاسم) أكسيد‏

עברית (Hebrew)
n. - ‮תחמוצת‬


 
 

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved.  Read more
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Columbia Encyclopedia. The Columbia Electronic Encyclopedia, Sixth Edition Copyright © 2003, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/  Read more
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Wikipedia. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Oxide" Read more
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