Redox Reactions and Oxidation Numbers

Practice flashcards covering the fundamentals of oxidation-reduction reactions, rules for oxidation numbers, and the five main types of redox reactions.

Redox Reaction

An electron transfer reaction abbreviated from oxidation-reduction, where one reactant loses an electron and another reactant gains that electron.

Oxidation

The process in which a substance loses one or more electrons.

Reduction

The process in which a substance gains one or more electrons.

Oxidizing Agent

A substance that acts to enhance oxidation by being reduced itself.

Reducing Agent

A substance that acts to enhance reduction by being oxidized itself.

Half Reaction

An equation representing either the oxidation or the reduction part of a redox process separately.

Oxidation Number

The charge an atom would have in a molecule or an ionic compound if electrons were completely transferred.

Free Elements Rule

Elements that are uncombined with other elements, such as $Na$, $Be$, or $P_4$, have an oxidation number of zero.

Monatomic Ion Rule

The oxidation number is equal to the charge on the ion, such as $Li^+$ being $+1$ or $Fe^{3+}$ being $+3$.

Oxidation Number of Oxygen

Usually $-2$ in most compounds, with the exception of $H_2O_2$ where it is $-1$.

Oxidation Number of Hydrogen

Usually $+1$ except when it is bonded to metals in binary compounds.

Group 1A Metals

Metals like lithium that always have an oxidation number of $+1$ when in a compound.

Group 2A Metals

Metals that always have an oxidation number of $+2$ when in a compound.

Sum of Oxidation Numbers (Neutral)

The sum of oxidation numbers of all atoms in a molecule must be equal to zero.

Sum of Oxidation Numbers (Ion)

The sum of oxidation numbers of all atoms in an ion must be equal to the charge on that ion.

Combination Reaction

A redox reaction where two or more reactants come together to form a single product.

Decomposition Reaction

A redox reaction where one reactant gives rise to two or more products.

Combustion Reaction

A reaction where oxygen is a reactant, often used to support burning or producing a flame.

Displacement Reaction

A reaction where one element replaces another element in a compound, often referred to as replacement.

Hydrogen Displacement

A subcategory of displacement where a metal replaces hydrogen in water or an acid.

Metal Displacement

A subcategory of displacement where a metal replaces another metal in a compound.

Halogen Displacement

A subcategory of displacement involving elements in Group 7 ($F_2 > Cl_2 > Br_2 > I_2$) displacing one another based on reactivity.

Activity Series

A guide or list used to determine if a metal or halogen is capable of displacing another in a reaction.

Disproportionation Reaction

A specific type of redox reaction where the same element is simultaneously oxidized and reduced.

Breath Analyzer Application

A real-world application of redox where alcohol reduces Chromium from a $+6$ oxidation state to a $+3$ state, changing the color to green.