Oxidation number OR Oxidation state | Rules to assign oxidation number | ch#6 | 9th class chemistry

Oxidation number OR Oxidation state | Rules to assign oxidation number | ch#6 | 9th class chemistry #oxidationstate #chemistry 1. *Elemental State:* For elements in their elemental state, the oxidation number is 0. For example, O2 or H2 have oxidation numbers of 0. 2. *Monatomic Ions:* The oxidation number of a monatomic ion is equal to the charge of the ion. For example, Na+ has an oxidation number of +1, while Cl- has an oxidation number of -1. 3. *Hydrogen:* In most compounds, hydrogen has an oxidation number of +1. However, in metal hydrides (compounds of hydrogen with metals), hydrogen has an oxidation number of -1. 4. *Oxygen:* In most compounds, oxygen has an oxidation number of -2. There are some exceptions, such as in peroxides (like H2O2) where oxygen has an oxidation number of -1. 5. *Alkali and Alkaline Earth Metals:* In compounds, alkali metals (Group 1) have an oxidation number of +1, and alkaline earth metals (Group 2) have an oxidation number of +2. 6. *Sum of Oxidation Numbers:* The sum of oxidation numbers in a neutral compound is equal to zero. In a polyatomic ion, the sum is equal to the charge of the ion. 7. *Fluorine:* In all compounds, fluorine has an oxidation number of -1 because it is the most electronegative element. 8. *Other Halogens:* Halogens (Cl, Br, I) generally have oxidation numbers of -1 in compounds, except when they are combined with more electronegative elements. 9. *Alkali Metal Hydrides:* In compounds like LiH or NaH, hydrogen has an oxidation number of -1. 10. *Polyatomic Ions:* For polyatomic ions, the sum of oxidation numbers equals the charge of the ion. For example, in the sulfate ion (SO4^2-), the sum of oxidation numbers (-2 for each oxygen, x for sulfur) equals -2.