Uranium 'breaks the rules again'

Work led by the research group of Professor Steve Liddle and published in the prestigious journal Nature Chemistry has reported a uranium dinitrogen molecule that, according to basic chemical theory, should not exist. The ...

Nanowire arrays could improve solar cells

Transparent electrodes are a critical component of solar cells and electronic displays. To collect electricity in a solar cell or inject electricity for a display, you need a conductive contact, like a metal, but you also ...

Researchers push for better policies around toxic chemicals

From high levels of lead found in school drinking water to industry sites releasing toxic heavy metals into the air, over 40 years of regulations in the United States have failed to protect human and environmental health ...

Enhancing the performance of metal-organic framework materials

Researchers at the group of Dr. Stefania Grecea at the University of Amsterdam's Research Priority Sustainable Chemistry have devised a way to enhance the practical performance of metal-organic frameworks (MOFs). By using ...

High reaction rates even without precious metals

Non-precious metal nanoparticles could one day replace expensive catalysts for hydrogen production. However, it is often difficult to determine what reaction rates they can achieve, especially when it comes to oxide particles. ...

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Oxide

An oxide is a chemical compound contaning at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides. Oxides result when elements are oxidized by oxygen in 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.

Virtually all elements burn in an atmosphere of oxygen, or an oxygen rich environment. In the presence of water and oxygen (or simply air), some elements - lithium, sodium, potassium, rubidium, caesium, strontium and barium - react rapidly, even dangerously, to give the hydroxides. In part for this reason, alkali and alkaline earth metals are not found in nature in their metallic, i.e., native, form. Caesium is so reactive with oxygen that it is used as a getter in vacuum tubes, and solutions of potassium and sodium, so called NaK are used to deoxygenate and dehydrate some organic solvents. The surface of most metals consist of oxides and hydroxides in the presence of air. A well known example is aluminium foil, which is coated with a thin film of aluminium oxide that passivates the metal, slowing further corrosion. The aluminium oxide layer can be built to greater thickness by the process of electrolytic anodising. Although solid magnesium and aluminium react slowly with oxygen at STP, they, like most metals, will burn in air, generating very high temperatures. As a consequence, finely grained powders of most metals can be dangerously explosive in air.

In dry oxygen, iron readily forms iron(II) oxide, but the formation of the hydrated ferric oxides, Fe2O3−2x(OH)x, that mainly comprise rust, typically requires oxygen and water. The production of free oxygen by photosynthetic bacteria some 3.5 billion years ago precipitated iron out of solution in the oceans as Fe2O3 in the economically-important iron ore hematite.

Due to its electronegativity, oxygen forms chemical bonds with almost all elements to give the corresponding oxides. So-called noble metals (common examples: gold, platinum) resist direct chemical combination with oxygen, and substances like gold(III) oxide must be generated by indirect routes.

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