Question

Name each of the following compounds, which contain polyatomic ions. a. \(\mathrm{NaMnO}_{4}\) b. AlPO \(_{4}\) c. \(\mathrm{CrCO}_{3}\) d. \(\mathrm{Ca}(\mathrm{ClO})_{2}\) e. \(\mathrm{BaCO}_{3}\) f. \(\mathrm{CaCrO}_{4}\)

Short answer

The names of the given compounds with polyatomic ions are as follows: a. Sodium permanganate b. Aluminum phosphate c. Chromium(III) carbonate d. Calcium hypochlorite e. Barium carbonate f. Calcium chromate

Step-by-step solution

List the common Polyatomic Ions

First, we need to remember and identify some common polyatomic ions and their chemical formulas: - Permanganate: \(\mathrm{MnO}_4^-\) - Phosphate: \(\mathrm{PO}_4^{3-}\) - Carbonate: \(\mathrm{CO}_3^{2-}\) - Hypochlorite: \(\mathrm{ClO}^-\) - Chromate: \(\mathrm{CrO}_4^{2-}\)

Name each compound

Now let's name each compound based on our knowledge of polyatomic ions and their formulas. Remember that we don't need to change suffixes as we do in covalent compounds: a. \(\mathrm{NaMnO}_{4}\) This compound is sodium permanganate because \(\mathrm{MnO}_{4}\) is the permanganate ion, and sodium is \(\mathrm{Na^{+}}\). b. \(\mathrm{AlPO}_{4}\) This compound is aluminum phosphate because \(\mathrm{PO}_{4}\) is the phosphate ion, and aluminum is \(\mathrm{Al^{3+}}\). c. \(\mathrm{CrCO_3}\) This compound is chromium(III) carbonate because \(\mathrm{CO}_{3}\) is the carbonate ion, and chromium here is \(\mathrm{Cr^{3+}}\). Here we mention the oxidation state of chromium, since it can have more than one oxidation state. d. \(\mathrm{Ca(ClO)_2}\) This compound is calcium hypochlorite because \(\mathrm{ClO}\) is the hypochlorite ion, and calcium is \(\mathrm{Ca^{2+}}\). e. \(\mathrm{BaCO}_{3}\) This compound is barium carbonate because \(\mathrm{CO}_{3}\) is the carbonate ion, and barium is \(\mathrm{Ba^{2+}}\). f. \(\mathrm{CaCrO}_{4}\) This compound is calcium chromate because \(\mathrm{CrO}_{4}\) is the chromate ion, and calcium is \(\mathrm{Ca^{2+}}\).

Key concepts

Polyatomic Ions

Polyatomic ions are ions that consist of two or more atoms bonded together, carrying a net charge due to the loss or gain of electrons. They play a crucial role in the naming of ionic compounds, as identifying the polyatomic ion within the compound helps us correctly name it without altering any suffixes.

Some common polyatomic ions, as listed in the exercise, include:

• Permanganate: \(\mathrm{MnO}_4^-\)
• Phosphate: \(\mathrm{PO}_4^{3-}\)
• Carbonate: \(\mathrm{CO}_3^{2-}\)
• Hypochlorite: \(\mathrm{ClO}^-\)
• Chromate: \(\mathrm{CrO}_4^{2-}\)

Recognizing these polyatomic ions in chemical formulas helps you seamlessly name compounds without the need to modify the names of the ions themselves. Simply identify the metal and the polyatomic ion to name the compound correctly.

Chemical Nomenclature

Chemical nomenclature is a systematic method used to name chemical compounds. It is essential for identifying and communicating chemical substances accurately and ensures that each compound has a unique name.

When naming ionic compounds, the name is composed of the name of the cation (positive ion) followed by the name of the anion (negative ion). For example, in \(\mathrm{NaMnO}_4\), sodium acts as the cation while permanganate is the anion, hence its name "sodium permanganate."

Unlike covalent compounds, where suffix changes occur based on the number of atoms, ionic compounds, especially those involving polyatomic ions, maintain the given name of the ion. Therefore, it’s crucial to be familiar with common ions and their charges to name compounds correctly.

Oxidation States

An oxidation state (or oxidation number) refers to the total number of electrons that an atom either gains or loses to form a chemical bond with another atom. Knowing the oxidation states helps predict compound formation and ensures proper naming, especially when an element can exist in multiple oxidation states.

In ionic compounds, the sum of the oxidation states of all atoms must equal the overall charge of the compound. For example, in \(\mathrm{CrCO}_3\), the oxidation state of chromium is \(+3\), which balances with the \(\mathrm{CO}_3^{2-}\) ion. Thus, the full name is "chromium(III) carbonate," where the Roman numeral indicates the specific oxidation state of chromium.

Understanding oxidation states is vital in chemical nomenclature because it clarifies which version of an element is present in the compound, particularly for metals with more than one potential oxidation state.