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what r oxidation states??(11th std chem.)

what r oxidation states??(11th std chem.)

Grade:12

2 Answers

Amit Askiitiansexpert
112 Points
13 years ago

Hi ,

The oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by integers, which can be positive, negative, or zero. In some cases the average oxidation state of an element is a fraction, such as 8/3 for iron in magnetite (Fe3O4). The highest oxidation state is +8 in the tetroxides of xenon, ruthenium and osmium, while the lowest is −4 for some elements in the carbon group.

The increase in oxidation state of an atom through a chemical reaction is known as an oxidation; a decrease in oxidation state is known as a reduction. Such reactions involve the formal transfer of electrons, a net gain in electrons being a reduction and a net loss of electrons being an oxidation. For pure elements, the oxidation state is zero.

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prashant madhukar
33 Points
13 years ago

Oxidation State

Oxidation state is a number assigned to an element in a compound according to some rules. This number enable us to describe oxidation-reduction reactions, and balancing redox chemical reactions. You are learning the skill to assign oxidation states (or oxidation numbers) to a variety of compounds and ions.

When an oxidation number is assigned to the element, it does not imply that the element in the compound acquires this as a charge, but rather that it is a convenient number to use for balancing chemical reactions. The guidelines for assigning oxidation states (numbers) are given below:

  • The oxidation state of any element such as Fe, H2, O2, P4, S8 is zero (0).
  • The oxidation state of oxygen in its compounds is -2, except for peroxides like H2O2, and Na2O2, in which the oxidation state for O is -1.
  • The oxidation state of hydrogen is +1 in its compounds, except for metal hydrides, such as NaH, LiH, etc., in which the oxidation state for H is -1.
  • The oxidation states of other elements are then assigned to make the algebraic sum of the oxidation states equal to the net charge on the molecule or ion.
  • The following elements usually have the same oxidation states in their compounds:
    • +1 for alkali metals - Li, Na, K, Rb, Cs;
    • +2 for alkaline earth metals - Be, Mg, Ca, Sr, Ba;
    • -1 for halogens except when they form compounds with oxygen or one another;
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