Question

Supply a systematic name for each of the following ternary ionic compounds: (a) \(\mathrm{LiMnO}_{4}\) (b) \(\operatorname{Sr}\left(\mathrm{ClO}_{2}\right)_{2}\) (c) \(\mathrm{BaCO}_{3}\) (d) \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\)

Short answer

(a) Lithium Permanganate; (b) Strontium Chlorite; (c) Barium Carbonate; (d) Ammonium Dichromate.

Step-by-step solution

Identify the Cation

The first step in naming a ternary ionic compound is to identify the cation (the positively charged ion) in the compound. For each of the given compounds: (a) In \(\mathrm{LiMnO}_{4}\), the cation is Lithium (Li). (b) In \(\operatorname{Sr}\left(\mathrm{ClO}_{2}\right)_{2}\), the cation is Strontium (Sr). (c) In \(\mathrm{BaCO}_{3}\), the cation is Barium (Ba). (d) In \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\), the cation is Ammonium (\(\mathrm{NH}_{4}^{+}\)).

Identify the Polyatomic Anion

Next, identify the anion, especially focusing on the polyatomic ions, which are more than one atom. For each compound: (a) In \(\mathrm{LiMnO}_{4}\), the anion is Permanganate (\(\mathrm{MnO}_{4}^{-}\)). (b) In \(\operatorname{Sr}\left(\mathrm{ClO}_{2}\right)_{2}\), the anion is Chlorite (\(\mathrm{ClO}_{2}^{-}\)). (c) In \(\mathrm{BaCO}_{3}\), the anion is Carbonate (\(\mathrm{CO}_{3}^{2-}\)). (d) In \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\), the anion is Dichromate (\(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\)).

Combine Cation and Anion Names

To form the systematic name of a ternary ionic compound, combine the cation name followed by the anion name. Note that the names do not require prefixes or changes except for specific polyatomic naming: (a) \(\mathrm{LiMnO}_{4}\) becomes Lithium Permanganate. (b) \(\operatorname{Sr}\left(\mathrm{ClO}_{2}\right)_{2}\) becomes Strontium Chlorite. (c) \(\mathrm{BaCO}_{3}\) becomes Barium Carbonate. (d) \(\left(\mathrm{NH}_{4}\right)_{2}\mathrm{Cr}_{2}\mathrm{O}_{7}\) becomes Ammonium Dichromate.

Key concepts

Ternary Ionic Compounds

Ternary ionic compounds are fascinating chemical structures composed of three different elements. This distinguishing feature arises because they include at least one polyatomic ion, a charged species made up of two or more atoms bonded together. Typically, these compounds contain a metal (cation) bonded to a polyatomic anion. Understanding and naming ternary ionic compounds requires correctly identifying both the cation and the polyatomic anion.
To name a ternary ionic compound, always write the name of the cation first, followed by the name of the anion. For instance, in lithium permanganate, "lithium" is the cation, while "permanganate" is the polyatomic anion. There are no prefixes like in molecular compounds, simplifying naming once identification is complete. Recognizing these compounds' structure and systematic naming rules can demystify the chemistry behind them and make them less intimidating.

Polyatomic Ions

Polyatomic ions are ions consisting of multiple atoms bonded together, often carrying a net charge. They are essential in forming ternary ionic compounds by combining with cations. Prefixes and suffixes often help distinguish different ions, an essential element in chemical nomenclature.
These ions can have varying charges and compositions, such as carbonate (\(CO_3^{2-}\)), chlorite (\(ClO_2^{-}\)), or chromate (\(CrO_4^{2-}\)). The naming conventions help identify the distinct characteristics of each polyatomic ion. For example, ions with one extra oxygen than the "ate" version get labeled "per...ate" as in permanganate (\(MnO_4^{-}\)). Similarly, removing one oxygen yields an "ite" ion, like chlorite.
Recognizing these ions and their variations is crucial for accurately naming and understanding ternary ionic compounds. Their presence contributes significantly to the diversity and behavior of these compounds in chemical reactions.

Systematic Naming

Systematic naming is a cornerstone of chemistry that ensures each compound has a unique and descriptive name. This process involves rules and conventions that offer clarity and uniformity across the scientific community. When it comes to ternary ionic compounds, systematic naming provides a framework for correctly identifying cations and polyatomic anions.
Each name follows a logical pattern, beginning with the cation and followed by the anion, reflecting the compound's composition and the ions involved. For example:

• Lithium in lithium permanganate (\(LiMnO_4\)) indicates the cation, and permanganate is the anion with a specific polyatomic arrangement.
• Strontium chlorite (\(Sr(ClO_2)_2\)) highlights the strontium cation linked to chlorite anions.

Systematic naming avoids redundancy and confusion, providing an intuitive yet precise system to address the vast array of possible compounds. Learning these conventions ensures clear communication and deeper insights into chemical properties and interactions.