Question

Name each of the following compounds: a. \(\mathrm{BaSO}_{3}\) b. \(\mathrm{NaNO}_{2}\) c. \(\mathrm{KMnO}_{4}\) d. \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{-}\)

Short answer

a. \(BaSO_{3}\) : Barium sulfite b. \(NaNO_{2}\) : Sodium nitrite c. \(KMnO_{4}\) : Potassium permanganate d. \(K_{2}Cr_{2}O_{7}\) : Potassium dichromate

Step-by-step solution

Identify Cations and Anions

Identify the individual cations and anions for each compound: a. \(\mathrm{BaSO}_{3}\) : Ba²⁺ is the cation (barium), and SO₃²⁻ is the anion (sulfite) b. \(\mathrm{NaNO}_{2}\) : Na⁺ is the cation (sodium), and NO₂⁻ is the anion (nitrite) c. \(\mathrm{KMnO}_{4}\) : K⁺ is the cation (potassium), and MnO₄⁻ is the anion (permanganate) d. \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) : K⁺ is the cation (potassium), and Cr₂O₇²⁻ is the anion (dichromate)

Name Each Compound

Using the cation and anion names, name each compound: a. \(\mathrm{BaSO}_{3}\) : Barium sulfite b. \(\mathrm{NaNO}_{2}\) : Sodium nitrite c. \(\mathrm{KMnO}_{4}\) : Potassium permanganate d. \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) : Potassium dichromate

Key concepts

Cations and Anions

In chemistry, understanding the concepts of cations and anions is crucial for naming ionic compounds. **Cations** are positively charged ions formed when an atom loses one or more electrons. For example, in the compound \( \mathrm{NaNO}_{2} \), sodium \( (\mathrm{Na}^+) \) is the cation because it has lost one electron.
**Anions**, on the other hand, are negatively charged ions formed when an atom gains electrons. A good example is the nitrite ion \( (\mathrm{NO}_2^-) \) in the same compound. It has gained an electron, thus carrying a negative charge.
When naming ionic compounds, the cation name is always written first followed by the anion name. Knowing the charge and behavior of these ions can help predict and understand the interactions within the compound. This system of naming ensures clear communication in the scientific community.

Chemical Nomenclature

Chemical nomenclature is the systematic method of naming chemical compounds. It relies on a standardized set of rules to ensure each compound is uniquely identified. When it comes to **ionic compounds**, the name often includes the cation followed by the anion. This sequence clearly reflects the components present in the compound.
For instance, when naming \( \mathrm{KMnO}_{4} \), we identify potassium \( (\mathrm{K}^+) \) as the cation and permanganate \( (\mathrm{MnO}_4^-) \) as the anion. The compound is named "potassium permanganate." Using such specific names prevents confusion and provides detailed information about the compound's structure.

• The cation retains its elemental name, such as "sodium" for \( \mathrm{Na}^+ \).
• The anion often has a modified name ending, such as "sulfite" for \( \mathrm{SO}_3^{2-} \).

This clear naming technique helps scientists around the world share and discuss chemical data without misunderstanding.

Polyatomic Ions

Polyatomic ions are ions consisting of two or more atoms bonded together that act as a single charged entity. Many common ionic compounds incorporate these complex ions. In the example of \( \mathrm{BaSO}_3 \), the **sulfite ion** \( (\mathrm{SO}_3^{2-}) \) behaves as a single unit with a net negative charge.
Polyatomic ions, like \( \mathrm{Cr}_2\mathrm{O}_7^{2-} \) in potassium dichromate, are widely used in various chemical reactions and have significant roles in both nomenclature and functionality of compounds. Knowing the common polyatomic ions and their corresponding charges is essential for proper naming and understanding chemical behavior.

• Many polyatomic ions end in "-ate" or "-ite," such as "nitrate" \( (\mathrm{NO}_3^-) \) or "sulfite" \( (\mathrm{SO}_3^{2-}) \).
• Memorizing these ions and their charges is helpful in predicting compound formulas.

By mastering these intricate ions, students can effortlessly name complex ionic compounds and gain insights into their chemical properties.