Oxidation Numbers

do not have exact physical meaning
useful for naming compounds, writing formulas, and balancing chem equations


Assigning Oxidation Numbers
	Shared electrons are assumed to belong to the more electronegative atom.

	1. Pure elements have oxidation number of 0
		Na, O2, P4, S8
	2. More electronegative in a binary m-compound is assigned number equal to negative charge 

it would have as ion. less electro is assigned number equal to positive charge as a cation.
	3. F has oxidation number of -1 in all compounds
	4. O has o# of -2 in almost all compounds
		exceptions: peroxides (H2O2, O2, o# is -1), compounds with F (OF2, o# is +2)
	5. H has +1 in all compounds with more electronegative elements. Has -1 in compounds with 

metals
	6. Sum of oxidation numbers of all atoms in a neutral compound is zero
	7. Sum of o# of all atoms in a polyatomic ion is equal to charge of ion
	8. Oxidation numbers can also be assigned to atoms in ionic compounds
	9. Monatomic ion has o# equal to charge of the ion
		Na+ has oxidation number of +1

	Can be used to determine possible compounds but do not prove existence of such compounds/
	+4 and +6 oxidation states of sulfur --> possible SO2 and SO3 compounds

	Stock System (use of roman numerals in nomenclature) is based on oxidation states. It is 

more practical for complicated compounds than prefix-based names.

	PCl3
		phosphorus trichloride, phosphorus(III) chloride
	N2O
		dinitrogen monoxide, nitrogen(I) oxide
	NO
		nitrogen monoxide, nitrogen(II) oxide
	PbO2
		lead dioxide, lead(IV) oxide