Assign oxidation numbers to each element in the following ions. (e) HPO4 2-

Verified step by step guidance

1. Assign the oxidation number of hydrogen (H) as +1.
2. Assign the oxidation number of oxygen (O) as -2.
3. Let the oxidation number of phosphorus (P) be x.
4. Set up the equation based on the ion's charge: 1 (for H) + x (for P) + 4(-2) (for O) = -2 (overall charge of the ion).
5. Solve the equation for x to find the oxidation number of phosphorus.

Key Concepts

Oxidation Numbers

Oxidation numbers are a way to keep track of electrons in chemical compounds. They indicate the degree of oxidation of an atom in a molecule, helping to identify how many electrons an atom has gained or lost. The rules for assigning oxidation numbers include that the oxidation number of an element in its elemental form is zero, and for monoatomic ions, it equals the charge of the ion.

Polyatomic Ions

Polyatomic ions are ions that consist of two or more atoms bonded together, which carry a net charge. In the case of HPO4 2-, it is a polyatomic ion known as hydrogen phosphate. Understanding the structure and charge of polyatomic ions is essential for correctly assigning oxidation numbers to the individual elements within the ion.

Sum of Oxidation Numbers

The sum of the oxidation numbers of all atoms in a molecule or ion must equal the overall charge of that species. For HPO4 2-, the total oxidation number must equal -2. This principle is crucial for determining the oxidation states of individual elements, as it provides a framework for balancing the oxidation numbers based on the known charge of the ion.