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An oxide (/ ˈ ɒ k s aɪ d /) is a chemical compound containing at least one oxygen atom and one other element [1] in its chemical formula. "Oxide" itself is the dianion (anion bearing a net charge of –2) of oxygen, an O 2– ion with oxygen in the oxidation state of −2. Most of the Earth's crust consists of oxides. Even materials ...
Download as PDF; Printable version; In other projects ... not pure elements in their standard state or allotropes. ... +2: 2 89 actinium: Ac +3: f-block groups 90 ...
A sesquioxide is an oxide of an element (or radical), where the ratio between the number of atoms of that element and the number of atoms of oxygen is 2:3. For example, aluminium oxide Al 2 O 3 and phosphorus(III) oxide P 4 O 6 are sesquioxides. Many sesquioxides contain a metal in the +3 oxidation state and the oxide ion O 2−, e.g ...
Many oxyanions of elements in lower oxidation state obey the octet rule and this can be used to rationalize the formulae adopted. For example, chlorine(V) has two valence electrons so it can accommodate three electron pairs from bonds with oxide ions. The charge on the ion is +5 − 3 × 2 = −1, and so the formula is ClO − 3.
Introductory chemistry uses postulates: the oxidation state for an element in a chemical formula is calculated from the overall charge and postulated oxidation states for all the other atoms. A simple example is based on two postulates, OS = +1 for hydrogen; OS = −2 for oxygen; where OS stands for oxidation state.
N.B. Pilling and R.E. Bedworth [2] suggested in 1923 that metals can be classed into two categories: those that form protective oxides, and those that cannot. They ascribed the protectiveness of the oxide to the volume the oxide takes in comparison to the volume of the metal used to produce this oxide in a corrosion process in dry air.
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Osmium forms compounds with oxidation states ranging from −2 to +8. The most common oxidation states are +2, +3, +4, and +8. The +8 oxidation state is notable for being the highest attained by any chemical element aside from iridium's +9 [1] and is encountered only in xenon, [2] [3] ruthenium, [4] hassium, [5] iridium, [6] and plutonium.