Question

Write the name of each of the following ionic substances, using -ous or -ic endings to indicate the charge of the cation. a. \(\mathrm{CoCl}_{2}\) d. \(\operatorname{sn} \mathrm{O}_{2}\) b. \(\mathrm{CrBr}_{3}\) e. \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) c. \(\mathrm{PbO}\) f. \(\mathrm{FeCl}_{3}\)

Short answer

3$ as the charge of \(\mathrm{Br}^{-}\) is -1) c. \(\mathrm{Pb}\) has a charge of +2 in \(\mathrm{PbO}\) (since the charge of \(\mathrm{O}^{2-}\) is -2) d. \(\operatorname{Sn}\) has a charge of +4 in \(\operatorname{sn} \mathrm{O}_{2}\) (since $2\times(-2)=-4$ as the charge of \(\mathrm{O}^{2-}\) is -2) e. \(\mathrm{Fe}\) has a charge of +3 in \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) (since $2\times+3=+6$ as the charge of \(\mathrm{Fe}\) and \(3\times(-2)=-6\) as the charge of \(\mathrm{O}^{2-}\) is -2) f. \(\mathrm{Fe}\) has a charge of +3 in \(\mathrm{FeCl}_{3}\) (since $3\times(-1)=-3$ as the charge of \(\mathrm{Cl}^{-}\) is -1) Finally, name each ionic substance using -ous or -ic endings. #tag_title#Step 3: Naming the ionic substances#tag_content# Here are the names of the ionic substances using -ous or -ic endings, based on the charge of the cations: a. \(\mathrm{CoCl}_{2}\) - Cobaltous chloride b. \(\mathrm{CrBr}_{3}\) - Chromic bromide c. \(\mathrm{PbO}\) - Plumbous oxide d. \(\mathrm{SnO}_{2}\) - Stannic oxide e. \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) - Ferric oxide f. \(\mathrm{FeCl}_{3}\) - Ferric chloride

Step-by-step solution

Identifying the cations

Firstly, identify the cation (positively charged ion) in each ionic substance listed. a. \(\mathrm{Co}\) in \(\mathrm{CoCl}_{2}\) b. \(\mathrm{Cr}\) in \(\mathrm{CrBr}_{3}\) c. \(\mathrm{Pb}\) in \(\mathrm{PbO}\) d. \(\operatorname{Sn}\) in \(\operatorname{sn} \mathrm{O}_{2}\) e. \(\mathrm{Fe}\) in \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) f. \(\mathrm{Fe}\) in \(\mathrm{FeCl}_{3}\) Now determine the charge of each cation.

Determining the charge of the cations

Determine the charge of the identified cations in each ionic substance: a. \(\mathrm{Co}\) has a charge of +2 in \(\mathrm{CoCl}_{2}\) (since \(2\times(-1)=-2\) as the charge of \(\mathrm{Cl}^{-}\) is -1) b. \(\mathrm{Cr}\) has a charge of +3 in \(\mathrm{CrBr}_{3}\) (since $3\times(-1)=-

Key concepts

Cation Charge

Understanding the cation charge is crucial when naming ionic compounds. A cation is a positively charged ion, and in an ionic bond, it typically pairs with an anion, which is negatively charged. The charge on a cation is determined by the number of electrons that have been lost relative to the neutral atom.

For instance, in the ionic compound \(\mathrm{CoCl}_{2}\), the cation is cobalt (\(\mathrm{Co}\)). To find the charge, look at the anion - in this case, chlorine (\(\mathrm{Cl}^{-}\)) which has a -1 charge. Since there are two chloride ions to balance the charge, cobalt must have a +2 charge to ensure the compound is electrically neutral. This means for every cobalt ion, there are two chloride ions, indicating a 1:2 ratio.

Knowing the cation charge is not only key for naming compounds but also for predicting the formulas of ionic compounds from the name and understanding their physical and chemical properties.

Ionic Substance Nomenclature

The nomenclature of ionic substances involves a systematic way of naming compounds so that their chemical formulas can be determined from their names, and vice versa. Classic nomenclature for transition metals uses the -ous or -ic endings to denote the charge of the cations with lower and higher oxidation states, respectively.

For example, iron (\(\mathrm{Fe}\)) can have multiple charges, but in \(\mathrm{Fe}_{2} \mathrm{O}_{3}\), it has a +3 charge because there are three oxide ions, each with a -2 charge, and to balance this, the two iron ions must have a total charge of +6 (\(2 \times +3 = +6\)). This is why iron with a +3 charge is named ferric. If it had a +2 charge, it would be called ferrous. Similarly, cobalt with a charge of +2 in \(\mathrm{CoCl}_{2}\) is known as cobaltous chloride, and with a +3 charge in other compounds, it would be called cobaltic.

When learning to name ionic substances, be mindful of these traditional naming conventions, as they provide key information about the chemical makeup of the compounds.

Chemical Formula

A chemical formula conveys essential information about the proportion of elements that make up a chemical compound. For ionic substances, the formula is based on the compound being electrically neutral, with total positive charges of cations equaling total negative charges of anions.

For example, let's take the chemical formula \(\mathrm{CrBr}_{3}\). It indicates that one chromium (\(\mathrm{Cr}\)) ion combines with three bromide (\(\mathrm{Br}^{-}\)) ions. Since each bromide ion has a -1 charge, the chromium cation must have a +3 charge to balance out the overall charge and achieve electrical neutrality. This is a simple yet powerful concept because, once you know the charge on the ions, you can deduce the ratios in which they combine.

Remember, keeping track of these charges is essential, as it ensures that the resulting compound obeys the laws of conservation of charge, guiding us to write correct chemical formulas for ionic substances.