Assign oxidation numbers to each atom in Borax, Na2B4O7, a mineral used in laundry detergent. (LO 4.18)

Verified step by step guidance

1. insert step 1> Identify the oxidation number of sodium (Na). Sodium is an alkali metal and typically has an oxidation number of +1.
2. insert step 2> Assign the oxidation number for oxygen (O). Oxygen usually has an oxidation number of -2 in compounds.
3. insert step 3> Let the oxidation number of boron (B) be x.
4. insert step 4> Write the equation based on the compound's neutrality: 2(+1) + 4(x) + 7(-2) = 0.
5. insert step 5> Solve the equation for x to find the oxidation number of boron.

Key Concepts

Oxidation Numbers

Oxidation numbers are assigned to atoms in a compound to indicate the degree of oxidation or reduction of each atom. They help in understanding electron transfer in redox reactions. 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

Borax contains the polyatomic ion B4O7^2-, which consists of boron and oxygen atoms. Understanding the structure and charge of polyatomic ions is crucial for assigning oxidation numbers correctly. Each atom within the polyatomic ion contributes to the overall charge, which must be balanced with the oxidation numbers assigned to the other elements in the compound.

Balancing Charges

When assigning oxidation numbers, it is essential to ensure that the sum of the oxidation numbers equals the overall charge of the compound. In the case of Borax, Na2B4O7, the sodium ions (Na+) contribute a +2 charge, which must be balanced by the oxidation numbers of the boron and oxygen atoms in the B4O7^2- ion. This balancing act is key to accurately determining the oxidation states.