NAMING IONIC COMPOUNDS Name Name the following compounds using the Stock Naming System.
The Correct Answer and Explanation is:
Of course. Here are the correct names for the ionic compounds on the worksheet, followed by a detailed explanation of the Stock Naming System.
Correct Answers
- CaCO₃ — Calcium carbonate
- KCl — Potassium chloride
- FeSO₄ — Iron(II) sulfate
- LiBr — Lithium bromide
- MgCl₂ — Magnesium chloride
- FeCl₃ — Iron(III) chloride
- Zn₃(PO₄)₂ — Zinc phosphate
- NH₄NO₃ — Ammonium nitrate
- Al(OH)₃ — Aluminum hydroxide
- CuC₂H₃O₂ — Copper(I) acetate
- PbSO₃ — Lead(II) sulfite
- NaClO₃ — Sodium chlorate
- CaC₂O₄ — Calcium oxalate
- Fe₂O₃ — Iron(III) oxide
- (NH₄)₃PO₄ — Ammonium phosphate
- NaHSO₄ — Sodium hydrogen sulfate
- Hg₂Cl₂ — Mercury(I) chloride
- Mg(NO₃)₂ — Magnesium nitrate
- CuSO₄ — Copper(II) sulfate
- NaHCO₃ — Sodium hydrogen carbonate
- NiBr₃ — Nickel(III) bromide
- Be(NO₃)₂ — Beryllium nitrate
- ZnSO₄ — Zinc sulfate (Note: The formula appears to be a typo “ZnSO” and has been interpreted as the common compound Zinc Sulfate, ZnSO₄).
Explanation of the Stock Naming System
The Stock Naming System is the standard method established by the International Union of Pure and Applied Chemistry (IUPAC) for naming ionic compounds. Its primary purpose is to provide an unambiguous name for every compound, especially for metals that can form more than one type of positive ion (cation).
An ionic compound consists of a positively charged cation (usually a metal) and a negatively charged anion (a nonmetal or a polyatomic ion). The naming process follows a clear set of rules:
1. Naming the Cation (Positive Ion):
The cation is always named first.
- Fixed-Charge Metals: For metals that form only one stable ion, such as those in Group 1 (e.g., Na⁺), Group 2 (e.g., Ca²⁺), and others like Aluminum (Al³⁺) and Zinc (Zn²⁺), you simply use the element’s name. For example, Ca in CaCO₃ is named “calcium.”
- Variable-Charge Metals: Many transition metals and some main group metals (like lead, Pb, and tin, Sn) can form multiple cations with different charges (e.g., iron can be Fe²⁺ or Fe³⁺). For these, the Stock system requires specifying the charge with a Roman numeral in parentheses immediately after the metal’s name. For example, in Fe₂O₃, the oxide anion (O²⁻) has a total charge of -6 (3 x -2). To balance this, the two iron ions must have a total charge of +6, meaning each is an Fe³⁺ ion. Therefore, its name is “iron(III).”
2. Naming the Anion (Negative Ion):
The anion is named second.
- Monatomic Anions: For anions consisting of a single nonmetal element, the ending of the element’s name is changed to “-ide.” For example, Cl becomes “chloride” and O becomes “oxide.”
- Polyatomic Anions: These are ions made of multiple atoms bonded together (e.g., SO₄²⁻, NO₃⁻, CO₃²⁻). They have specific names that must be memorized, such as “sulfate,” “nitrate,” and “carbonate.” If the polyatomic anion contains hydrogen, the word “hydrogen” is added before its name (e.g., HCO₃⁻ is “hydrogen carbonate”).
By combining the cation and anion names according to these rules, we can create a unique and descriptive name for any ionic compound.
