Oxidation Number | California State University, Chico

University:
California State University, Chico
Course:
CHEM 111 | General Chemistry I
Academic year:

2023
Views:

187

Pages:

1
Author:

Hallie Randolph

The oxidation number (or oxidation state) of an element in a compound or ion is a number assigned to the element that represents its degree of oxidation or reduction. It indicates the number of electrons that an atom either gains, loses, or shares when it forms chemical bonds. The oxidation number can be positive, negative, or zero, depending on the nature of the chemical bond and the rules for assigning oxidation states. Here are some key rules for determining oxidation numbers: 1. Pure elements: The oxidation number of any pure element (e.g., O₂, H₂, N₂) is zero. 2. Monatomic ions: The oxidation number of a monatomic ion is equal to its charge (e.g., Na⁺ has an oxidation number of +1, Cl⁻ has an oxidation number of -1). 3. Oxygen: The oxidation number of oxygen in most compounds is -2, but it is -1 in peroxides (e.g., H₂O₂). 4. Hydrogen: The oxidation number of hydrogen is +1 when bonded to non-metals and -1 when bonded to metals. 5. Alkali metals (Group 1): The oxidation number of alkali metals (e.g., Li, Na, K) in compounds is +1. 6. Alkaline earth metals (Group 2): The oxidation number of alkaline earth metals (e.g., Mg, Ca) in compounds is +2. 7. Fluorine: The oxidation number of fluorine in compounds is always -1. 8. Sum of oxidation numbers: The sum of the oxidation numbers of all atoms in a neutral compound is zero. In a polyatomic ion, the sum of the oxidation numbers equals the charge of the ion.