Question

Name each of the following ionic or covalent compounds: a. \(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\) antiperspirant b. \(\mathrm{CaCO}_{3}\) antacid c. \(\mathrm{N}_{2} \mathrm{O}^{\text {" }}\) laughing gas," inhaled anesthetic d. \(\mathrm{Na}_{3} \mathrm{PO}_{4}\) cathartic e. \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}\) fertilizer f. \(\mathrm{Fe}_{2} \mathrm{O}_{3}\) pigment

Short answer

a) Aluminum sulfate, b) Calcium carbonate, c) Dinitrogen monoxide, d) Sodium phosphate, e) Ammonium sulfate, f) Iron(III) oxide.

Step-by-step solution

- Identify cation and anion for \(\(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\)\) and name the compound

In \(\(\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}\)\), the cation is \(\(\mathrm{Al}^{3+}\)\) (aluminum ion), and the anion is \(\(\mathrm{SO}_{4}^{2-}\)\) (sulfate ion). The name of the compound is aluminum sulfate.

- Identify cation and anion for \(\(\mathrm{CaCO}_{3}\)\) and name the compound

In \(\(\mathrm{CaCO}_{3}\)\), the cation is \(\(\mathrm{Ca}^{2+}\)\) (calcium ion), and the anion is \(\(\mathrm{CO}_{3}^{2-}\)\) (carbonate ion). The name of the compound is calcium carbonate.

- Identify elements for \(\(\mathrm{N}_{2}\mathrm{O}\)\) and name the compound

In \(\(\mathrm{N}_{2}\mathrm{O}\)\), there are two nitrogen atoms and one oxygen atom. The name of the compound is dinitrogen monoxide, commonly known as laughing gas.

- Identify cation and anion for \(\(\mathrm{Na}_{3}\mathrm{PO}_{4}\)\) and name the compound

In \(\(\mathrm{Na}_{3}\mathrm{PO}_{4}\)\), the cation is \(\(\mathrm{Na}^{+}\)\) (sodium ion), and the anion is \(\(\mathrm{PO}_{4}^{3-}\)\) (phosphate ion). The name of the compound is sodium phosphate.

- Identify cation and anion for \(\(\left(\mathrm{NH}_{4}\right)_{2}\mathrm{SO}_{4}\)\) and name the compound

In \(\(\left(\mathrm{NH}_{4}\right)_{2}\mathrm{SO}_{4}\)\), the cation is \(\(\mathrm{NH}_{4}^{+}\)\) (ammonium ion), and the anion is \(\(\mathrm{SO}_{4}^{2-}\)\) (sulfate ion). The name of the compound is ammonium sulfate.

- Identify cation and anion for \(\(\mathrm{Fe}_{2}\mathrm{O}_{3}\)\) and name the compound

In \(\(\mathrm{Fe}_{2}\mathrm{O}_{3}\)\), the cation is \(\(\mathrm{Fe}^{3+}\)\) (iron(III) ion), and the anion is \(\(\mathrm{O}^{2-}\)\) (oxide ion). The name of the compound is iron(III) oxide, commonly known as ferric oxide.

Key concepts

Ionic Compounds

Ionic compounds are formed when atoms transfer electrons, resulting in positively charged ions (cations) and negatively charged ions (anions). These ions are held together by strong electrostatic forces. Ionic compounds typically form between metals and nonmetals. For example, in aluminum sulfate \(\text{Al}_{2}(\text{SO}_{4})_{3}\), aluminum acts as the cation (Al^{3+}) and sulfate as the anion (SO_{4}^{2-}). Similarly, calcium carbonate (CaCO_{3}) consists of calcium ions (Ca^{2+}) and carbonate ions (CO_{3}^{2-}). Key characteristics of ionic compounds include high melting and boiling points, and they often dissolve in water to form electrolytes.

• They form large crystal lattice structures.
• Examples: sodium chloride (NaCl), magnesium oxide (MgO).

Covalent Compounds

Covalent compounds form when atoms share pairs of electrons. This type of bonding typically occurs between nonmetals. In covalent compounds, the shared electrons allow each atom to achieve a stable electron configuration. An example is dinitrogen monoxide (N_{2}O), commonly known as laughing gas, where two nitrogen atoms share electrons with one oxygen atom. Covalent compounds can exist in various states (solid, liquid, gas) under standard conditions and often have lower melting and boiling points compared to ionic compounds.

• They do not usually conduct electricity.
• Examples include water (H_{2}O), carbon dioxide (CO_{2}).

Chemical Nomenclature

Chemical nomenclature is the system used to name chemical substances. For ionic compounds, the cation (positive ion) name is given first followed by the anion (negative ion). For example, in sodium phosphate (Na_{3}PO_{4}), 'sodium' is the cation and 'phosphate' is the anion. For covalent compounds, numerical prefixes are used to indicate the number of atoms. For instance, 'dinitrogen monoxide' indicates two nitrogen atoms and one oxygen atom (N_{2}O). The nomenclature rules help in systematically identifying the compounds and their compositions.

• For metals that can form more than one positive ion, a Roman numeral indicates the charge, e.g., iron(III) oxide (Fe_{2}O_{3}).
• Prefixes include: mono-, di-, tri-, tetra-, etc.

Cation and Anion Identification

Identifying cations and anions is crucial in naming ionic compounds. The cation is always a positive ion, usually derived from a metal, and the anion is a negative ion, often non-metal or polyatomic. For example, in ammonium sulfate ((NH_{4})_{2}SO_{4}), ammonium (NH_{4}^{+}) is the cation and sulfate (SO_{4}^{2-}) is the anion. In ferric oxide (Fe_{2}O_{3}), iron(III) (Fe^{3+}) is the cation and oxide (O^{2-}) is the anion.

• Cations: Al^{3+}, Ca^{2+}, Na^{+}, NH_{4}^{+}, Fe^{3+}, etc.
• Anions: SO_{4}^{2-}, CO_{3}^{2-}, PO_{4}^{3-}, O^{2-}, etc.

Common Chemical Names

Many chemical compounds have common names that are used in everyday language. These names often differ from their systematic IUPAC names. For aluminum sulfate, there is no common name widely used, but calcium carbonate is known as limestone or simply chalk. Dinitrogen monoxide is called laughing gas due to its euphoric effects. Sodium phosphate has multiple uses but is commonly called TSP (trisodium phosphate) in cleaning contexts. Ammonium sulfate is commonly used as a fertilizer. Lastly, iron(III) oxide is often called rust, particularly in contexts involving its brownish appearance on iron and steel.

• Calcium carbonate (CaCO_{3}) – limestone.
• Dinitrogen monoxide (N_{2}O) – laughing gas.
• Sodium phosphate (Na_{3}PO_{4}) – TSP in cleaning.
• Iron(III) oxide (Fe_{2}O_{3}) – rust.