Question

Name the following ionic compounds: (a) \(\mathrm{Li}_{2} \mathrm{O}\), (b) \(\mathrm{FeCl}_{3}\), (c) \(\mathrm{NaClO}\), (d) \(\mathrm{CaSO}_{3}\), (e) \(\mathrm{Cu}(\mathrm{OH})_{2}\), (f) \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2}\), (g) \(\mathrm{Ca}\left(\mathrm{CH}_{3} \mathrm{COO}\right)_{2}\), (h) \(\mathrm{Cr}_{2}\left(\mathrm{CO}_{3}\right)_{3}\), (i) \(\mathrm{K}_{2} \mathrm{CrO}_{4},(\mathbf{j})\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}\).

Short answer

(a) Lithium oxide (b) Iron(III) chloride (c) Sodium hypochlorite (d) Calcium sulfite (e) Copper(II) hydroxide (f) Iron(II) nitrate (g) Calcium acetate (h) Chromium(III) carbonate (i) Potassium chromate (j) Ammonium sulfate

Step-by-step solution

Identify the cation and anion in each compound

For each compound, identify the cation, which is listed first, and the anion, which is listed second. Keep in mind that some ions may be polyatomic (consisting of more than one atom) and it's important to recognize the correct grouping for these ions. (a) Li (cat.) + O (an.) (b) Fe (cat.) + Cl (an.) (c) Na (cat.) + ClO (an.) (d) Ca (cat.) + SO3 (an.) (e) Cu (cat.) + OH (an.) (f) Fe (cat.) + NO3 (an.) (g) Ca (cat.) + CH3COO (an.) (h) Cr (cat.) + CO3 (an.) (i) K (cat.) + CrO4 (an.) (j) NH4 (cat.) + SO4 (an.)

Name the cations and anions

For most cases, you will simply use the name of the elements changing suffix of anion to "-ide": (a) Lithium (cat.) + Oxide (an.) However, for other cases that include polyatomic ions, you must know their proper names: (b) Iron (cat.) + Chloride (an.) (c) Sodium (cat.) + Hypochlorite (an.) (d) Calcium (cat.) + Sulfite (an.) (e) Copper (cat.) + Hydroxide (an.) (f) Iron (cat.) + Nitrate (an.) (g) Calcium (cat.) + Acetate (an.) (h) Chromium (cat.) + Carbonate (an.) (i) Potassium (cat.) + Chromate (an.) (j) Ammonium (cat.) + Sulfate (an.) Note that when a transition metal ion has a variable charge, specify its oxidation state as a Roman numeral in parentheses after the name: (b) Iron(III) (cat.) + Chloride (an.) (f) Iron(II) (cat.) + Nitrate (an.)

Combine the names of cations and anions to name the compounds

Join the names of the cations and anions to get the complete name for each compound: (a) Lithium oxide (b) Iron(III) chloride (c) Sodium hypochlorite (d) Calcium sulfite (e) Copper(II) hydroxide (f) Iron(II) nitrate (g) Calcium acetate (h) Chromium(III) carbonate (i) Potassium chromate (j) Ammonium sulfate

Key concepts

Cation and Anion Identification

Identifying the cation and anion in any ionic compound is crucial to naming it correctly. The cation is always listed first, followed by the anion. Cations are typically positively charged ions, and anions are negatively charged ions. To identify the ions in a compound:

• Look at the formula. The first element or group of elements represents the cation.
• The remaining part of the compound tells you the anion.

Some ions are not single elements but consist of groups of atoms bound together with an overall charge. These are called polyatomic ions. For example, the formula \(\mathrm{CaSO}_3\) consists of the cation Calcium (\(\mathrm{Ca}^{2+}\)) and the anion Sulfite (\(\mathrm{SO}_3^{2-}\)). Here, it is critical to identify that "SO₃" is a single, unified anion instead of separate sulfur and oxide ions. Once you understand the makeup of cations and anions, it's easier to move to the next step, which involves using this information to properly name ionic compounds.

Polyatomic Ions

Polyatomic ions are ions that consist of more than one atom. Unlike single-atom ions, they keep their structure and name as a whole when forming compounds. It is essential to memorize common polyatomic ions and their charges because they appear frequently in chemistry.

• Examples of polyatomic ions include Nitrate (\(\mathrm{NO}_3^-\)), Sulfate (\(\mathrm{SO}_4^{2-}\)), and Acetate (\(\mathrm{CH}_3\mathrm{COO}^-\)).
• When identifying polyatomic ions within a compound, look for specific groupings of atoms that frequently recur, such as \(\mathrm{CO}_3^{2-}\) for carbonate.

Let's look at \(\mathrm{Fe(NO}_3)_2\): This compound has the cation formula \(\mathrm{Fe}^{2+}\) and a polyatomic anion \(\mathrm{NO}_3^-\) known as Nitrate. In this compound, each Iron trails two Nitrates to neutralize the charge, showcasing how these ions combine in fixed proportions. Recognizing these groupings will help you seamlessly name and understand ionic compounds containing polyatomic ions.

Naming Ionic Compounds

Naming ionic compounds involves combining the names of the cations and anions. Follow these simple rules to successfully name them:

• For the cation, use the element's name as is. If it’s a metal with a variable charge, like transition metals, include its oxidation state in Roman numerals.
• For the anion, if it's a single element, change the suffix to "-ide."
• If the anion is a polyatomic ion, use the established name of the ion, such as \'Nitrate\' or \'Sulfate\'.

For instance, consider \(\mathrm{FeCl}_3\): It contains Iron, which is a metal with variable charges. The compound is named Iron(III) Chloride because the Iron here has a +3 charge to balance the three Chlorides each with a -1 charge. Another example is \(\mathrm{( ext{NH}_4)_2SO}_4\): It includes the cation Ammonium and the polyatomic anion Sulfate, making the complete name Ammonium Sulfate. Understanding how to systematically combine these names will empower you to decode and name ionic compounds efficiently and accurately.