Oxidation State

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Chem

Cegep/2

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177 words

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2 minutes

Hypothetical charge of an atom if all of its bonds to other atoms are ionic, i.e. if electrons are completely transferred in the direction indicated by electronegativity
Syn. oxidation number

Sum of oxidation numbers in a molecule = 0
Sum of oxidation numbers in an ion = charge of ion

Atom	Oxidation number	Examples
Atom in an element	0	$\mathrm{Na},\mathrm{Hg},\mathrm{H}{\phantom{A}}_2,\mathrm{Br}{\phantom{A}}_2,\mathrm{P}{\phantom{A}}_4,\mathrm{S}{\phantom{A}}_8$
Monatomic ion	Charge of ion	$\mathrm{Li}{\phantom{A}}^{+}\to +1$ $\mathrm{Ba}{\phantom{A}}^{2+}\to +2$ $\mathrm{Br}{\phantom{A}}^{-}\to -1$
Alkali metals	+1	$\mathrm{Na}$ in $\mathrm{NaOH}$
Alkaline earth metals	+2	$\mathrm{Be}$ in $\mathrm{BeO}$
Halogens other than $\mathrm{F}$	Normal -> -1 With oxygen -> +	$\mathrm{Cl}$ in $\mathrm{CCl}{\phantom{A}}_4\to -1$ $\mathrm{Cl}$ in $\mathrm{HClO}{\phantom{A}}_4\to +7$
Aluminum	+3	$\mathrm{Al}$ in $\mathrm{Al}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_3$
Oxygen	-2 (except peroxide)	$\mathrm{O}$ in $\mathrm{H}{\phantom{A}}_2\mathrm{O}\to -2$ $\mathrm{O}$ in $\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_2\to -1$
Hydrogen	Covalent -> +1 Ionic -> -1	$\mathrm{H}$ in $\mathrm{CH}{\phantom{A}}_4\to +1$ $\mathrm{H}$ in $\mathrm{NaH}\to -1$
Fluorine	-1	$\mathrm{F}$ in $\mathrm{NaF}$

Contributors

Ajitani Hifumi

Changelog

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