Overview
This lecture covers how to name different types of ionic compounds, including binary ionic compounds, compounds with polyatomic ions, and those involving transition metals with variable charges.
Naming Binary Ionic Compounds
- Ionic compounds contain a metal and a non-metal.
- Name the metal first using its element name (e.g., Na as sodium).
- Name the non-metal second, modifying its ending to "-ide" (e.g., Cl as chloride).
- Examples: NaCl is sodium chloride; MgBr₂ is magnesium bromide.
- Some further examples: AlF₃ is aluminum fluoride; CaO is calcium oxide; Sr₃N₂ is strontium nitride; BaS is barium sulfide.
Naming Ionic Compounds with Polyatomic Ions
- Polyatomic ions are groups of atoms with a single charge and a unique name.
- The name of the metal comes first, followed by the polyatomic ion’s name.
- Examples: Li₂SO₄ is lithium sulfate; Na₂CO₃ is sodium carbonate.
- Barium hydroxide (Ba(OH)₂) and potassium acetate (KC₂H ₃O₂) are named by recognizing their polyatomic ions.
- NH₄NO₃ is ammonium nitrate, with both parts being polyatomic ions.
Naming Ionic Compounds with Transition Metals (Variable Charges)
- Many transition metals can have more than one positive charge.
- Use Roman numerals in parentheses to indicate the metal’s charge in the compound.
- Example: FeCl₂ is iron(II) chloride (Fe²⁺), FeCl₃ is iron(III) chloride (Fe³⁺).
- Copper(I) bromide (CuBr) and copper(II) bromide (CuBr₂) are named similarly using charges.
- Chromium(II) sulfide (CrS) and chromium(III) sulfide (Cr₂S₃); tin(II) oxide (SnO) and tin(IV) oxide (SnO₂).
- Lead(II) sulfate (PbSO₄) and lead(IV) carbonate (Pb(CO₃)₂) follow the same pattern.
Roman Numeral Basics
- I = 1, II = 2, III = 3, IV = 4 (5-1), V = 5, VI = 6 (5+1), VII = 7 (5+2).
- Roman numerals are used up to VII for indicating metal charges.
Key Terms & Definitions
- Binary Ionic Compound — Compound with two elements: a metal and a non-metal.
- Polyatomic Ion — A charged group of covalently bonded atoms.
- Transition Metal — Metals that may have more than one possible charge.
- Roman Numerals — System used to show the charge of metals in compound names.
Action Items / Next Steps
- Memorize the most common polyatomic ions and their names.
- Practice naming ionic compounds, focusing on those with polyatomic ions and transition metals.
- Review the use of Roman numerals for indicating metal charges.