Problem 185 - Introductory Chemistry Atoms First

Question

The polyatomic ion \(\mathrm{MnO}_{4}^{2-}\) is listed in your book as permanganate. What would be the name of \(\mathrm{MnO}_{3}^{2-} ?\)

Step-by-Step Solution

Answer

Manganese(IV) Trioxide

Step 1: Identify the elements

In the \(\mathrm{MnO}_{3}^{2-}\) ion, we have two elements: Manganese (Mn) and Oxygen (O).

Step 2: Determine the charge of Mn

In the \(\mathrm{MnO}_{3}^{2-}\) ion, the total charge is -2. Oxygen has a charge of -2, and since there are 3 oxygen atoms, the total charge of oxygen in the ion is -6. Thus, the charge of Manganese must be +4, so that the overall charge of the ion is -2.

Step 3: Find the name of Oxygen atoms in the ion with appropriate prefix

We have 3 oxygen atoms, which gives us the prefix "tri". The name for Oxygen in the polyatomic ion is Oxide.

Step 4: Name the ion

Combine the name of the metal, the charge of Mn in roman numerals within brackets, and the name of the Oxygen atoms with the appropriate prefix. This gives us the name Manganese(IV) Trioxide for the \(\mathrm{MnO}_{3}^{2-}\) ion.

Key Concepts

Ion Charge Determination

Determining the charge of ions is crucial for understanding their behavior in chemical reactions. When dealing with polyatomic ions like \( \mathrm{MnO}_{3}^{2-} \), it's important to first identify the known charge and then figure out the unknown elements' charges. In \( \mathrm{MnO}_{3}^{2-} \), Oxygen typically has a charge of \(-2\). Given there are three oxygen atoms, the total charge from oxygen is \(-6\). Since the overall ion charge is \(-2\), Manganese must have a charge that balances this to \(-2\) overall. Hence, Manganese has a \(+4\) charge. Calculating charges involves ensuring that all charges add up to the total ion charge. This ensures overall charge neutrality or matches a specified charge in polyatomic ions.

Naming Polyatomic Ions

Naming polyatomic ions involves a few important steps. We need to recognize the central elements and their roles. In \( \mathrm{MnO}_{3}^{2-} \), we have Manganese (Mn) and Oxygen (O). With polyatomic ions, we may have prefixes and suffixes that relate to the number of certain atoms.

• The prefix 'tri-' indicates three oxygen atoms.
• The suffix '-oxide' follows the word indicating oxygen in this context.

Combining these aspects with the central atom gives the name for the ion. We also reflect the oxidation state of metals like Manganese in Roman numerals. Therefore, the name becomes Manganese(IV) Trioxide, where (IV) is the oxidation state of Manganese. This systematic naming not only aids in identification but also ensures transparency in representing chemical compounds.

Chemistry Nomenclature

Chemistry nomenclature is an organized system used to name chemical substances. It ensures that every chemical compound has a unique and descriptive name. Polyatomic ions, like \( \mathrm{MnO}_{3}^{2-} \), follow specific naming conventions that help identify their composition and structure.
Key elements of nomenclature include:

• The root name of the most characteristic part, usually the central atom's name such as 'Manganese'.
• The number of atoms, indicated by prefixes (e.g., 'tri-' for three as in Trioxide).
• Oxidation states of transition metals in Roman numerals, such as (IV), following the metal name.

With this organized framework, chemistry nomenclature allows chemists to name compounds efficiently and uniformly, instantly relaying important information about the compound’s makeup and characteristics.