Name each ionic compound. In each of these compounds, the metal forms more than one type of ion. (a) \(\mathrm{HgBr}_{2}\) (b) \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) (c) \(\mathrm{CuI}_{2}\) (d) \(\mathrm{SnCl}_{4}\)

Understanding the naming of ionic compounds is pivotal in the field of chemistry and a critical skill for students. Chemical nomenclature, the standardized approach of naming chemical compounds, adheres to specific rules laid out by the International Union of Pure and Applied Chemistry (IUPAC). When working with ionic compounds, like those presented in the exercise, it's essential to distinguish between the cation (a positively charged ion) and the anion (a negatively charged ion). A metal typically forms the cation, and a non-metal forms the anion.

For metals that can exhibit more than one ionic charge, such as iron in Fe_2O_3, the charge is indicated using Roman numerals in parentheses right after the name of the metal. For the compound HgBr_2, mercury has a charge that must be calculated based on the charge of the bromine ion. Bromine as a halogen has a -1 charge, which means mercury here must have a +2 charge to balance out the bromine in the compound, making the correct name mercury(II) bromide. For CuCl_2, the chlorine carries a -1 charge, so copper must have a +2 charge to neutralize the overall compound, leading to the name copper(II) chloride.

Oxidation states, also known as oxidation numbers, indicate the degree of oxidation of an atom in a compound. They are assigned to atoms as a tool to keep track of electron transfer during chemical reactions, and follow a set of rules. For example, the oxidation state of an atom in a pure element is always zero. For a simple monoatomic ion, the oxidation state is equal to the charge on the ion. In compounds, hydrogen generally has an oxidation state of +1, and oxygen typically has an oxidation state of -2.

In the case of ionic compounds with transition metals, such as Fe_2O_3, the oxidation state of the metal ion is not immediately apparent and must be deduced. For Fe_2O_3, with oxygen having an oxidation state of -2 and since there are three oxygen atoms contributing to a total of -6, the two iron atoms must collectively have an oxidation state of +6, making the oxidation state of each iron atom +3. This leads us to name the compound iron(III) oxide. Understanding how to determine oxidation states is crucial to correctly naming compounds and predicting their chemical behavior.

The periodic table is more than a mere list of elements; it's a powerful tool for predicting the properties of elements, including those vital for determining the ionic charges in compounds. Elements are arranged by increasing atomic number and by chemical properties. One of the most critical trends for naming ionic compounds is the typical ionic charge that elements in a group (vertical column) exhibit. For instance, the alkaline earth metals in Group 2 typically have a +2 charge when they form ions, while halogens in Group 17 typically form ions with a -1 charge.

In naming ionic compounds, it is useful to know these trends, which can often indicate the charges of ions in the compounds. For example, when looking at SnCl_4, knowing that chlorine (a halogen) often has a -1 charge allows us to deduce that since there are four chlorine atoms, tin must have a +4 charge to balance the charges, resulting in the name tin(IV) chloride. Familiarizing oneself with these periodic table trends enables a more intuitive understanding of compound formation and simplifies the naming process.