Ionic Compound Naming Guide

Overview

This lecture covers how to name ionic compounds, including binary compounds, those with polyatomic ions, and compounds with transition metals requiring Roman numerals.

Naming Binary Ionic Compounds

• Ionic compounds are made of a metal and a non-metal.
• Name the metal first using its element name.
• Name the non-metal second, changing its ending to "-ide" (e.g., chloride, bromide).
• No prefixes (mono-, di-, etc.) are used for ionic compounds.

Compounds with Polyatomic Ions

• Polyatomic ions must be memorized or referenced from a provided list.
• Name the metal (or ammonium) first, then the polyatomic ion as is (e.g., sulfate, carbonate).
• Examples: Li₂SO₄ is lithium sulfate; Na₂CO₃ is sodium carbonate.

Transition Metals and Roman Numerals

• Transition metals (and some other metals) can have multiple charges.
• Use Roman numerals to indicate the metal's charge in the compound name.
• Determine the metal’s charge based on anion charges and compound neutrality.
• Example: FeCl₂ is iron(II) chloride, FeCl₃ is iron(III) chloride.

Naming Examples with Roman Numerals

• For CuBr, copper balances a -1 charge, so it’s copper(I) bromide.
• For CuBr₂, copper balances two -1 charges, so it’s copper(II) bromide.
• For Cr₂S₃, with three sulfides (-2 each), the chromium charge is +3, making it chromium(III) sulfide.
• For SnO, tin has a +2 charge, so it’s tin(II) oxide; for SnO₂, tin is +4, so tin(IV) oxide.

Roman Numeral Basics

• I = 1, II = 2, III = 3, IV = 4, V = 5, VI = 6, VII = 7.
• Numerals before V subtract, after V add (IV = 4, VI = 6).

Additional Polyatomic Ion Examples

• Ba(OH)₂ is barium hydroxide.
• KC₂H₃O₂ is potassium acetate.
• Zn(ClO₄)₂ is zinc perchlorate.
• NH₄NO₃ is ammonium nitrate.
• PbSO₄ is lead(II) sulfate; Pb(CO₃)₂ is lead(IV) carbonate.

Key Terms & Definitions

• Binary Ionic Compound — Ionic compound with one metal and one non-metal.
• Polyatomic Ion — Ion made of multiple atoms acting as a unit with a single charge.
• Transition Metal — Metals with multiple possible oxidation states.
• Roman Numerals — Symbols used to indicate metal charge in compound names.

Action Items / Next Steps

• Memorize common polyatomic ions.
• Practice naming compounds with variable-charge metals using Roman numerals.
• Review and practice basic Roman numeral usage.