Redox Reactions and Types of Chemical Reactions

Vocabulary flashcards covering oxidation numbers, rules for assigning oxidation numbers, redox concepts, oxidizing and reducing agents, and the four main types of chemical reactions.

Oxidation Number

A value assigned to an element in a substance that helps track changes involving electrons during a chemical reaction.

Free Element Rule

The rule stating that an element in its free or elemental form has an oxidation number of $0$ (e.g., $Mg = 0$, $Cu = 0$, $Na = 0$, $O_2 = 0$, $H_2 = 0$).

Monatomic Ion Rule

The rule stating that a monatomic ion has an oxidation number equal to its charge (e.g., $Na^+ = +1$, $Mg^{2+} = +2$, $Al^{3+} = +3$, $Cl^- = -1$, $O^{2-} = -2$).

Oxygen Oxidation Number Rule

Oxygen usually has an oxidation number of $-2$ in compounds (e.g., $MgO$), with exceptions in peroxides, superoxides, and compounds with fluorine.

Hydrogen Oxidation Number Rule

Hydrogen has an oxidation number of $+1$ when bonded to nonmetals (e.g., $H_2O$) and $-1$ when bonded to metals in metal hydrides (e.g., $NaH$).

Fluorine Oxidation Number Rule

Fluorine always has an oxidation number of $-1$ in all of its compounds.

Halogen Oxidation Number Rule

Chlorine, bromine, and iodine are usually $-1$ in binary compounds, but may have positive oxidation numbers when combined with oxygen or other halogens.

Polyatomic Ion Rule

The rule stating that the sum of the oxidation numbers of all atoms in a polyatomic ion equals the overall charge of the ion (e.g., the total for $SO_4^{2-}$ equals $-2$).

Oxidation

The process in a chemical reaction where the oxidation number of an element increases due to the loss of electrons.

Reduction

The process in a chemical reaction where the oxidation number of an element decreases due to the gain of electrons.

Reducing Agent

A substance that causes another substance to be reduced while itself being oxidized.

Oxidizing Agent

A substance that causes another substance to be oxidized while itself being reduced.

Redox Reaction

A chemical reaction in which oxidation and reduction occur simultaneously.

Non-Redox Reaction

A chemical reaction in which no oxidation number changes occur for any of the elements involved.

Combination Reaction

A chemical reaction in which two or more substances combine to form one product, following the general form $A + B \rightarrow AB$.

Decomposition Reaction

A chemical reaction in which one substance breaks down into two or more simpler substances, following the general form $AB \rightarrow A + B$.

Single Replacement Reaction

A chemical reaction in which one element replaces another element in a compound, following the general form $A + BC \rightarrow AC + B$.

Double Replacement Reaction

A chemical reaction in which the components of two compounds exchange partners, following the general form $AB + CD \rightarrow AD + CB$.