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. \(\operatorname{FeBr}_{2}\) b. \(cos\) c. \(C O_{2} S_{3}\) d. \(\operatorname{SnO}_{2}\) e. \(\mathrm{Hg}_{2} \mathrm{Cl}_{2}\) f. \(\mathrm{HgCl}_{2}\)

Short answer

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

Step-by-step solution

Identify the cations and anions

In this step, we will recognize the cations and anions in each given ionic substance. a. \(\operatorname{FeBr}_{2}\) has Fe as the cation and Br as the anion. b. "\(cos\)" is not a valid chemical formula so there is no answer for this. c. \(C O_{2} S_{3}\) has Co as the cation and S as the anion. d. \(\operatorname{SnO}_{2}\) has Sn as the cation and O as the anion. e. \(\mathrm{Hg}_{2} \mathrm{Cl}_{2}\) has Hg as the cation and Cl as the anion. f. \(\mathrm{HgCl}_{2}\) has Hg as the cation and Cl as the anion.

Find the charges of the cations and anions

We need to know the charges of the anions and cations to write proper names for these compounds. a. Br (bromide) has a charge of -1. c. S (sulfide) has a charge of -2. d. O (oxide) has a charge of -2. e. and f. Cl (chloride) has a charge of -1. The charges of the cations: a. Iron (Fe) can have multiple stable charges like +2 and +3. c. Cobalt (Co) can have charges of +2 and +3. d. Tin (Sn) can have charges of +2 and +4. e. and f. Mercury (Hg) can have charges of +1 (as mercurous) and +2 (as mercuric).

Determine the charge of the cation and write names of compounds

Based on charges of anions and possible charges of cations, we'll find the cation's charge and name the compounds using Roman numerals to show the charge of the cation. a. In \(\operatorname{FeBr}_{2}\), bromide has a -1 charge. To balance with two bromides, iron must have a +2 charge. The compound name is Iron(II) Bromide. c. In \(C O_{2} S_{3}\), sulfide has a -2 charge. To balance the total charge of 3 sulfides (-6), cobalt must have a +3 charge. The compound name is Cobalt(III) Sulfide. d. In \(\operatorname{SnO}_{2}\), oxide has a -2 charge. To balance with two oxides (-4 charge), tin must have a +4 charge. The compound name is Tin(IV) Oxide. e. In \(\mathrm{Hg}_{2} \mathrm{Cl}_{2}\), chloride has a -1 charge. But, there are two mercury atoms with the same charge sharing two chlorides. Mercury must have a +1 charge in this case. The compound name is Mercury(I) Chloride. f. In \(\mathrm{HgCl}_{2}\), chloride has a -1 charge. To balance with two chlorides (-2 charge), mercury must have a +2 charge. The compound name is Mercury(II) Chloride.

Key concepts

Cations and Anions

In the world of chemistry, **cations** and **anions** play crucial roles in the formation of ionic compounds. Simply put, **cations** are positively charged ions, while **anions** are negatively charged ions. This charge occurs due to the loss or gain of electrons.
Cations often form when a metal loses electrons. For instance, in \( ext{Fe} \), the iron loses electrons to become \( ext{Fe}^{2+}\) or \( ext{Fe}^{3+}\). These are examples of cations. Meanwhile, anions form when non-metals gain electrons, such as bromide in \( ext{Br}^{-}\).

• Cations have a few electrons compared to protons, leading to a net positive charge.
• Anions have extra electrons, resulting in a net negative charge.

Understanding which elements in a compound act as cations or anions is the first step in naming ionic compounds correctly.

Roman Numerals in Chemistry

In naming ionic compounds, **Roman numerals** are employed to denote the charge on transition metals. Transition metals can have multiple oxidation states. Using Roman numerals helps indicate which specific charge the metal ion possesses in that compound.
For example, iron can exist as \( ext{Fe}^{2+}\) or \( ext{Fe}^{3+}\), so when naming, we use Roman numerals such as Iron(II) or Iron(III) to distinguish them. This practice is essential to avoid ambiguity.

• Roman numeral "I" corresponds to a charge of +1.
• "II" signifies a charge of +2.
• "III" represents a charge of +3, and so on.

This system ensures precise communication in formulas and adds clarity to writing and interpreting chemical names.

Charge Balancing in Ionic Compounds

**Charge balancing** is a vital concept in forming ionic compounds. It ensures that the total positive charge is equal to the total negative charge in the compound, creating a stable structure.
To achieve charge balance, we look at the charges on cations and anions and adjust their ratios accordingly. For instance, in \( ext{FeBr}_{2}\), bromide has a charge of -1. Since there are two bromides, the total negative charge is -2. To balance this, the iron cation must have a charge of +2, resulting in Iron(II) Bromide.

• Each positive charge must be matched by a corresponding negative charge.
• Correct charge balancing is key to creating neutral compounds.
• Ensuring charge balance helps in determining the correct formula and name of the compound.

This principle not only aids in understanding compound formation but is essential for correctly identifying and naming ionic substances.