Question

Write the name of each of the following ionic substances, using the system that includes a Roman numeral to specify the charge of the cation. a. \(\mathrm{FeI}_{3}\) b. \(\mathrm{MnCl}_{2}\) c. \(\mathrm{HgO}\) d. \(\mathrm{Cu}_{2} \mathrm{~S}\) e. \(\mathrm{CoO}\) f. \(\operatorname{SnBr}_{4}\)

Short answer

a. Iron(III) Iodide b. Manganese(II) Chloride c. Mercury(II) Oxide d. Copper(I) Sulfide e. Cobalt(II) Oxide f. Tin(IV) Bromide

Step-by-step solution

Identify cation and anion

Cation: \(\mathrm{Fe}\) (Iron); Anion: \(\mathrm{I}\) (Iodide)

Determine charge of the cation

In \(\mathrm{FeI}_{3}\), there are three iodide ions, each with a charge of -1. Thus, the iron cation must have a charge of +3 to balance the three iodide ions.

Write the name of the ionic substance

Iron(III) Iodide b. \(\mathrm{MnCl}_{2}\)

Identify cation and anion

Cation: \(\mathrm{Mn}\) (Manganese); Anion: \(\mathrm{Cl}\) (Chloride)

Determine charge of the cation

In \(\mathrm{MnCl}_{2}\), there are two chloride ions, each with a charge of -1. Thus, the manganese cation must have a charge of +2 to balance the two chloride ions.

Write the name of the ionic substance

Manganese(II) Chloride c. \(\mathrm{HgO}\)

Identify cation and anion

Cation: \(\mathrm{Hg}\) (Mercury); Anion: \(\mathrm{O}\) (Oxide)

Determine charge of the cation

In \(\mathrm{HgO}\), there is one oxide ion with a charge of -2. Thus, the mercury cation must have a charge of +2 to balance the oxide ion.

Write the name of the ionic substance

Mercury(II) Oxide d. \(\mathrm{Cu}_{2} \mathrm{~S}\)

Identify cation and anion

Cation: \(\mathrm{Cu}\) (Copper); Anion: \(\mathrm{S}\) (Sulfide)

Determine charge of the cation

In \(\mathrm{Cu}_{2\mathrm{~S}}\), there is one sulfide ion with a charge of -2. Since there are two copper ions, each copper ion must have a charge of +1 to balance the sulfide ion.

Write the name of the ionic substance

Copper(I) Sulfide e. \(\mathrm{CoO}\)

Identify cation and anion

Cation: \(\mathrm{Co}\) (Cobalt); Anion: \(\mathrm{O}\) (Oxide)

Determine charge of the cation

In \(\mathrm{CoO}\), there is one oxide ion with a charge of -2. Thus, the cobalt cation must have a charge of +2 to balance the oxide ion.

Write the name of the ionic substance

Cobalt(II) Oxide f. \(\operatorname{SnBr}_{4}\)

Identify cation and anion

Cation: \(\mathrm{Sn}\) (Tin); Anion: \(\mathrm{Br}\) (Bromide)

Determine charge of the cation

In \(\operatorname{SnBr}_{4}\), there are four bromide ions, each with a charge of -1. Thus, the tin cation must have a charge of +4 to balance the four bromide ions.

Write the name of the ionic substance

Tin(IV) Bromide

Key concepts

Cation Charge Determination

Understanding how to determine the charge of the cation in an ionic compound is crucial for naming the compound accurately. The cation is the positively charged ion in the compound. It's necessary to find out its charge to ensure that the ionic compound is balanced. Ionic compounds are neutral overall, meaning that the total positive charge must equal the total negative charge.
To determine the cation's charge, follow these steps:

• Identify the anion (the negatively charged ion) and know its charge.
• Calculate the total negative charge by multiplying the anion charge by its subscript—this is the number of anions in the formula.
• The cation's charge is then the total positive charge required to balance this negative charge in the compound.

For instance, in \( \text{FeI}_3 \), iodide (I) has a -1 charge, and there are three iodide ions, giving a total of -3. Therefore, the iron (Fe) cation must have a +3 charge to balance it out.

Roman Numerals in Chemistry

In chemistry, especially when dealing with transition metals, Roman numerals indicate the charge of the cation in the compound's name. This system helps differentiate ions that can have more than one possible charge.
For example:

• Iron (Fe) can form \( \text{Fe}^{2+} \) or \( \text{Fe}^{3+} \) ions. These are indicated as Iron(II) and Iron(III) respectively.
• Copper (Cu) can have charges of \(+1\) or \(+2\), written as Copper(I) and Copper(II).

When naming an ionic compound, the Roman numeral is placed in parentheses immediately after the cation's name. This clarity is crucial because it specifies which ion you are referring to, avoiding any confusion in chemical communication. So for \( \text{FeI}_3 \), the compound is named Iron(III) Iodide because the iron ion is \( \text{Fe}^{3+} \).

Chemical Nomenclature Rules

Chemical nomenclature is a set of standardized rules used to name chemical compounds. This clarity ensures that everyone understands what compounds are being referenced, just by reading the name.
Key rules for naming ionic compounds include:

• The metal (cation) is always named first, followed by the non-metal (anion).
• The anion typically ends in '-ide,' like chloride (Cl) or oxide (O).
• If the cation can have multiple charges (common with transition metals), include the charge in Roman numerals, e.g., Copper(II) Sulfide for \( \text{Cu}S \) because copper here has a +2 charge.

With these rules, the names reflect the chemical structure and composition of the substances, aiding in the correct identification and usage in various chemical reactions or discussions.