Question

Write the name for each of the following substances, using the -ous/-ic notation. a. \(\operatorname{SnS}\) b. \(\operatorname{sn} S_{2}\) c. \(\operatorname{CoCl}_{3}\) d. \(\operatorname{Col}_{2}\) e. \(\mathrm{HgBr}_{2}\) f. \(\mathrm{Hg}_{2} \mathrm{Br}_{2}\)

Short answer

a. stannous sulfide b. stannic sulfide c. cobaltic chloride d. cobaltous iodide e. mercurous bromide f. mercuric bromide

Step-by-step solution

Understand -ous/-ic notation

In chemistry, the -ous and -ic notation is used to indicate the oxidation state or charge of the metal ion in a compound. The -ous suffix corresponds to the lower oxidation state, while the -ic suffix denotes the higher oxidation state of the metal in the compound.

Determine the oxidation state of the metal ion in each compound

To determine the oxidation state of the metal ion, we can use the charges of the ions involved in the compound. The charges need to balance, so considering the charge of the other ion can help determine the oxidation state of the metal ion a. \(\operatorname{SnS}\): Tin (Sn) forms a sulfide (S) ion. Sulfide ion has a charge of -2, so tin must have a charge of +2. b. \(\operatorname{SnS}_{2}\): In this compound, there are two sulfide ions, so the total negative charge is -4. This means that tin should have a +4 charge. c. \(\operatorname{CoCl}_{3}\): Cobalt (Co) forms a chloride (Cl) ion. Chloride ion has a charge of -1. Here we have three chloride ions, so the cobalt should have a +3 charge. d. \(\operatorname{CoI}_{2}\): In this compound, cobalt forms iodide (I) ions. Iodide ions have a charge of -1. We have two iodide ions, so cobalt must have a +2 charge. e. \(\mathrm{HgBr}_{2}\): Mercury (Hg) forms a bromide (Br) ion. Bromide ions have a charge of -1. We have two bromide ions, so mercury must have a +2 charge. f. \(\mathrm{Hg}_{2} \mathrm{Br}_{2}\): Mercury is in a different form, where it combines with another mercury ion to form \(\mathrm{Hg}_{2}^{2+}\). Each bromide ion has a charge of -1, and since we have two bromide ions, the \(\mathrm{Hg}_{2}^{2+}\) ion has an overall +2 charge.

Write the names using the -ous/-ic notation

Based on the oxidation state of the metal ion, we can now write the names of these compounds. a. \(\operatorname{SnS}\): Since tin has a charge of +2, use the -ous suffix. The name is stannous sulfide. b. \(\operatorname{SnS}_{2}\): Since tin has a charge of +4, use the -ic suffix. The name is stannic sulfide. c. \(\operatorname{CoCl}_{3}\): Since cobalt has a charge of +3, use the -ic suffix. The name is cobaltic chloride. d. \(\operatorname{CoI}_{2}\): Since cobalt has a charge of +2, use the -ous suffix. The name is cobaltous iodide. e. \(\mathrm{HgBr}_{2}\): Since mercury has a charge of +2, use the -ous suffix. The name is mercurous bromide. f. \(\mathrm{Hg}_{2} \mathrm{Br}_{2}\): Since mercury has a combined charge of +2, use the -ic suffix. The name is mercuric bromide.

Key concepts

Oxidation States

Oxidation states are like a bookkeeping tool in chemistry that help us understand how electrons are distributed in compounds. For metals, they are crucial in determining how the metal can bond with other elements, especially non-metals. Metals in compounds can exhibit different oxidation states, meaning they can lose different numbers of electrons to form positive ions. The oxidation state of an element is indicated by a positive or negative number that represents the charge of the ion formed by that element. Knowing the common oxidation states is essential when naming compounds, especially those that involve metals with variable oxidation states. For instance, copper can have oxidation states of +1 and +2, while iron may exhibit +2 or +3. These differences in oxidation states are what give a compound distinct names under the -ous/-ic system of nomenclature. To figure out the oxidation state of a metal in a compound, you need to understand the charges of all involved ions and how they balance in the compound's overall structure. Remember that in a stable compound, all the positive and negative charges must add up to zero to keep the compound neutral.

Metal Ions

Metal ions are positively charged ions formed when a metal loses electrons. These play a vital role in both chemical and biological processes. In a chemical compound, metal ions are often paired with negative ions to form salts. These ions play a key role in the formation and reactivity of compounds. The formation of metal ions is due to metals tending to lose electrons to achieve a stable electron configuration. The charge on a metal ion correlates directly with its oxidation state. For example, when a tin atom loses two electrons, it forms a \( ext{Sn}^{2+}\) ion, reflecting an oxidation state of +2. Metal ions vary in terms of charge and size, which affects how they interact with other ions and molecules. This interaction is crucial for the nomenclature using the -ous/-ic notation since the charge of the metal ion determines the suffix applied in naming.

-ous/-ic Notation

The -ous/-ic notation is a classical way of denoting different oxidation states of the same metal in a compound. In this system, the suffix -ous is used for the lower oxidation state, while -ic is used for the higher oxidation state. This naming helps differentiate between the chemical behavior and properties of the two forms. For instance:

• When cobalt has an oxidation state of +2, it is referred to as cobaltous. In chemical notation, this is for compounds like \(\text{CoI}_2\), named cobaltous iodide.
• Conversely, when cobalt has a +3 oxidation state, it takes the name cobaltic, as in \(\text{CoCl}_3\), called cobaltic chloride.

This system is particularly helpful for metals that can form more than one type of cation. It is worth noting that the -ous/-ic system is gradually being replaced by the Stock system, which uses Roman numerals to indicate the charge of the ion. Nonetheless, understanding the -ous/-ic notation remains useful, especially when dealing with older chemical literature and texts.