Chemistry(1st grade of high school): Theory: Oxidation number- Writing chemical formulas and introduction to the nomenclature of compounds

Oxidation number- Writing chemical formulas and introduction to the nomenclature of compounds

The names and symbols of the main monatomic and polyatomic ions are given below:

TABLE 2.3: Nomenclature of the main monatomic ions

Cl- chloride or chloride	O2- oxygen or oxide
Br- bromide or bromide	S2- sulfide or sulfide
I- iodide or iodide	N3- nitrogen or nitride
F- fluoride or fluoride	P3- phosphorous or phosphide
H- hydrogen or hydride

TABLE 2.4: Nomenclature of the main polyatomic ions

NO3- nitrate	CN- cyanide (cyanide )	HCO3- bicarbonate
CO32- carbonate	ClO4- perchlorate	HPO42- hydrogen phosphate
SO42- sulfate	ClO3- chlorate	H2PO4- diphosphate
PO43- phosphate	ClO2- chlorite	МnO4- permanganate
OH- hydroxide	ClO- hypochlorite	Cr2O72- dichromate
NH4+ ammonium	HSO4- hydrogen sulfate	CrO42- chromate

Oxidation number of an atom in a covalent compound:>

It defines the apparent charge that will be obtained by the atom if the shared electron pairs are assigned to the most electronegative atom.

The oxidation number of an ion in an ionic compound:

It is the actual charge of the ion.

TABLE 2.5: Common A.O. values of elements in their compounds

Metals		Nonmetals
Na, K, Li, Ag	+ 1	F	-1
Ba, Ca, Mg, Zn	+2	H	+1 (-1)
Al	+3	O	-2( -1,+2)
Cu, Hg	+ 1,+2	CI, Br, I	-1(+1, +3, +5, +7)
Fe, Ni	+2, +3	S	-2 (+4, + 6)
Pb, Sn	+2,+4	N, P	-3 (+3, +5)
Mn	+2, +4, +7	C, Si	-4,+4
Cr	+3, +6

Rules for calculating number of oxidation:

1. Each element in a free state has A.O equal to zero

2. H in its compounds has A.O equal to +1, except for its compounds with metals (hydrides) which has -1.

3. F in its compounds always has A.O equal to -1.

4. O in its compounds has A.O equal to -2, except the peroxides (having the group -O-O-), in which it has -1, and the compound OF2 (fluorine oxide), in which has +2.

5. Alkalis, e.g. Na, K, always have A.O. +1, and alkaline earths, e.g. Ba, Ca, always have A.O. +2.

6. The algebraic sum of the A.O of all atoms in a compound is equal to zero.

7. The algebraic sum of the A.O of all atoms in a polyatomic ion is equal to the charge of the ion.

The molecular formula of the compound is AψBx.

Note that:

a. if any index is 1, then it is omitted.

For the nomenclature in the following links:

(in my country, which is in Europe, we have different rules, so I tried to find the most helpful websites with theory, videos and exercises).