Difference between revisions of "Oxide"
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==Types== | ==Types== | ||
| − | All metals form oxides. Lower oxides of [[transition | + | All metals form oxides. Lower oxides of [[transition metal]]s tend to have color to them, while higher transition metal oxides are black due to a nonstoichiometric composition, or white due to the lack of d-shell electrons. Other metal oxides are often white due to the complete lack of d-shell electrons. Most metal oxides are basic, and will combine with water to form [[hydroxide]]s. Few of these, however, are soluble in water, save for the oxides of [[alkali metal]]s and thallium(I). Some metal oxides are amphoteric, meaning that they can be both acidic and basic. [[Aluminium oxide]] is the most common example. Some higher oxides of metals are acidic and will form oxoacids or oxoacid anions. Some common examples are [[chromium trioxide|chromium(VI) oxide]], which forms [[chromic acid]] when dissolved, and [[chromate]]s with many other metal ions, and [[manganese heptoxide]], which forms [[permanganate]]s. More commonly, however, they form with heavier transition metals, such as [[tantalum]] and [[tungsten]]. |
Some nonmetals form oxides, which tend to be a [[gas]] at normal temperatures, though some are solid or liquid. Most nonmetal oxides are [[Acid|acidic]], and many will combine with water to form an acid. Most nonmetal oxides are soluble in water. A few, however, are insoluble, notably [[carbon dioxide]] and [[sulfur dioxide]]. These can both be captured by [[Base|basic]] solutions and stored as [[carbonate]]s and [[sulfite]]s, respectively. | Some nonmetals form oxides, which tend to be a [[gas]] at normal temperatures, though some are solid or liquid. Most nonmetal oxides are [[Acid|acidic]], and many will combine with water to form an acid. Most nonmetal oxides are soluble in water. A few, however, are insoluble, notably [[carbon dioxide]] and [[sulfur dioxide]]. These can both be captured by [[Base|basic]] solutions and stored as [[carbonate]]s and [[sulfite]]s, respectively. | ||
| − | When considered 'ions', an oxide has -2 charge per oxygen, except in [[ | + | When considered 'ions', an oxide has -2 charge per oxygen, except in [[peroxide]]s, where both oxygen atoms have a charge of -1 each. Superoxide ions contain two oxygen atoms with an overall charge of -1, forming a [[radical]]. One example of a metal oxide is [[copper(II) oxide]], with the formula CuO. All metals can form oxides, but some form oxides more easily than others. For example: [[Iron(III) oxide|rust]] forms on iron easily, but gold is not normally oxidized by the oxygen in the air. |
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| + | ==Preparation== | ||
| + | Oxides can be formed by burning or exposing an element in an oxygen-rich atmosphere. | ||
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| + | Thermal decomposition of carbonates, hydroxides, and other organic salts at very high temperatures, in a kiln or furnace will give the desired oxide. | ||
==References== | ==References== | ||
<references/> | <references/> | ||
===Relevant Sciencemadness threads=== | ===Relevant Sciencemadness threads=== | ||
| + | *[http://www.sciencemadness.org/talk/viewthread.php?tid=3227 Color changing iron oxide] | ||
[[Category:Types of chemical]] | [[Category:Types of chemical]] | ||
Latest revision as of 14:49, 9 July 2018
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An oxide is a type of chemical which contains oxygen bonded to another element. The terminology is usually used to refer to inorganic compounds, where the oxygen is not part of a polyatomic anion.
Types
All metals form oxides. Lower oxides of transition metals tend to have color to them, while higher transition metal oxides are black due to a nonstoichiometric composition, or white due to the lack of d-shell electrons. Other metal oxides are often white due to the complete lack of d-shell electrons. Most metal oxides are basic, and will combine with water to form hydroxides. Few of these, however, are soluble in water, save for the oxides of alkali metals and thallium(I). Some metal oxides are amphoteric, meaning that they can be both acidic and basic. Aluminium oxide is the most common example. Some higher oxides of metals are acidic and will form oxoacids or oxoacid anions. Some common examples are chromium(VI) oxide, which forms chromic acid when dissolved, and chromates with many other metal ions, and manganese heptoxide, which forms permanganates. More commonly, however, they form with heavier transition metals, such as tantalum and tungsten.
Some nonmetals form oxides, which tend to be a gas at normal temperatures, though some are solid or liquid. Most nonmetal oxides are acidic, and many will combine with water to form an acid. Most nonmetal oxides are soluble in water. A few, however, are insoluble, notably carbon dioxide and sulfur dioxide. These can both be captured by basic solutions and stored as carbonates and sulfites, respectively.
When considered 'ions', an oxide has -2 charge per oxygen, except in peroxides, where both oxygen atoms have a charge of -1 each. Superoxide ions contain two oxygen atoms with an overall charge of -1, forming a radical. One example of a metal oxide is copper(II) oxide, with the formula CuO. All metals can form oxides, but some form oxides more easily than others. For example: rust forms on iron easily, but gold is not normally oxidized by the oxygen in the air.
Preparation
Oxides can be formed by burning or exposing an element in an oxygen-rich atmosphere.
Thermal decomposition of carbonates, hydroxides, and other organic salts at very high temperatures, in a kiln or furnace will give the desired oxide.
