Oxidation States

Oxidation state tells us the degree of oxidation (loss of electrons) of an atom.

It is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic (no covalent).

The oxidation state may be positive, negative or zero.

According to wikipedia…

The oxidation state, sometimes referred to as oxidation number, describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. Conceptually, the oxidation state, which may be positive, negative or zero, is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic, with no covalent component.

Table of contents

I wiil talk about the following topics:

  • Oxidation state simple definition
  • Oxidation states rules
  • Oxidation states and redox reactions
  • How can oxidation states be used to identify redox reactions
  • How to find oxidation state of elements
  • How to find oxidation state of compounds
  • How to find oxidation states of transition metals
  • How to write oxidation states
  • How to assign oxidation states to compounds
  • How to calculate oxidation states

Oxidation state simple definition

The oxidation state of an atom can be defined as the hypothetical charge that would be held by that atom if all of its bonds to other atoms were completely ionic in nature.

Oxidation states rules

Rules For Assigning Oxidation Numbers

  • The oxidation state of a pure element is always zero.
  • The oxidation state for a pure ion is equivalent to its ionic charge.
  • The sum of the oxidation states for all atoms of a neutral molecule must add up to zero.

Oxidation states and redox reactions

Redox stands for Reduction and Oxidation reactions and signifies the transfer of electrons within a reaction; in these reactions, the oxidation states of at least two elements will change during the reaction.

Redox reactions are comprised of two parts, a reduced half and an oxidized half, that always occur together.

The reduced half gains electrons and the oxidation number decreases, while the oxidized half loses electrons and the oxidation number increases.

How can Oxidation States Be Used To Identify Redox Reactions

Calculate the oxidation number of each atom in the reaction.

To identify a redox reaction, we must first calculate the oxidation number of each atom in the reaction.

If there is a change in oxidation number, then the reaction is a redox reaction.

If there is no change in oxidation number, then the reaction is not a redox reaction.

How to Find Oxidation State Of Elements

The oxidation state is equal to the net charge on the ion

The oxidation state of a free element (uncombined element) is zero.

For a simple (monoatomic) ion, the oxidation state is equal to the net charge on the ion.

For example, Cl– has an oxidation state of -1.

When present in most compounds, hydrogen has an oxidation state of +1 and oxygen an oxidation state of −2.

How to Calculate Oxidation States

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Materials: Oxidation States
Oxidation States
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