Oxidation Numbers Review

These flashcards cover key concepts regarding oxidation numbers, including definitions, rules, and examples.

Oxidation Number

An assigned charge to a molecule's elements that indicates the distribution of electron density within the molecule.

Oxidation

The process in which an atom loses electrons, resulting in an increase in oxidation number.

Reduction

The process in which an atom gains electrons, resulting in a decrease in oxidation number.

Diatomic Elements

Elements that naturally exist as diatomic molecules, such as Cl2, O2, and N2.

Monatomic Ion

An ion consisting of a single atom with a positive or negative charge.

Polyatomic Ion

An ion composed of two or more atoms that are covalently bonded and carry a charge.

Electronegative

The tendency of an atom to attract electrons; nonmetals are generally more electronegative than metals.

Oxygen Oxidation State

In compounds, oxygen typically has an oxidation state of -2.

Hydrogen Oxidation State

In compounds, hydrogen typically has an oxidation state of +1, except in metal hydrides.

Sum of Oxidation Numbers

In a neutral compound, the sum of the oxidation numbers must equal zero; for charged compounds, it must equal the charge.

Calcium Hydroxide Oxidation Numbers

In Ca(OH)2, Ca is +2, O is -2, and H is +1; total equals zero.

Nitrate Ion Oxidation Numbers

In NO3-, the oxidation number of nitrogen is +5, considering three oxygen atoms at -2 each.

Sulfate Ion Oxidation Numbers

In SO4^2-, the oxidation number of sulfur is +6, with four oxygen atoms each at -2.

Alkali Metals Oxidation State

Group 1 alkali metals always have an oxidation state of +1.

Balancing Redox Reactions

Assigning oxidation numbers is essential for balancing chemical redox reactions.

Reducing Agent

The species that donates electrons in a redox reaction and is oxidized.

Oxidizing Agent

The species that accepts electrons in a redox reaction and is reduced.