Overview
This lecture introduces the process for naming ionic compounds that contain transition metals using Roman numerals to indicate the metal's charge.
Transition Metals and Their Ions
- Transition metals are elements in the central block of the periodic table.
- These metals can form multiple ions with different positive charges (e.g., Fe²⁺ and Fe³⁺).
- Non-transition metals like sodium and magnesium generally form only one ion with a fixed charge.
- Some metals outside the transition block (like tin and lead) also form multiple ions.
Naming Rules for Ionic Compounds with Transition Metals
- When naming compounds with transition metals, use Roman numerals to show the charge of the metal ion.
- Example: FeCl₃ could be iron(III) chloride if iron is in the 3+ state.
- To determine the Roman numeral, calculate the charge on the metal ion by balancing the total charges in the compound.
- The anion's charge is usually known and helps determine the metal ion's charge.
Step-by-Step Example: FeCl₃
- Chlorine (Cl) always forms a 1– ion; three Cl⁻ gives a total of 3–.
- The metal (Fe) must balance this with a 3+ charge, so it's Fe³⁺ (iron(III)).
- Name: iron(III) chloride.
When to Use Roman Numerals
- Use Roman numerals for metals that can form more than one type of ion.
- Do not use Roman numerals for metals that form only one ion (e.g., sodium, potassium, calcium, aluminum).
Special Cases: Silver and Zinc
- Silver (Ag) always forms Ag⁺, and zinc (Zn) always forms Zn²⁺.
- Do not use Roman numerals when naming compounds with Ag or Zn.
- Example: AgCl is "silver chloride," not "silver(I) chloride."
Key Terms & Definitions
- Transition Metal — a metal element capable of forming multiple ions with different charges.
- Roman Numeral — notation in parentheses indicating the charge of a transition metal in a compound.
- Ion — an atom or group of atoms with a positive or negative charge.
- Anion — a negatively charged ion.
- Cation — a positively charged ion.
Action Items / Next Steps
- Review the next video on practice problems for naming compounds with transition metals.