Lecture on Naming Ionic Compounds

Introduction

• Lecturer: Dr. Kent
• Focus of the Lesson: Naming ionic compounds from their formulas.
• Continuation of series on ionic compounds.

Key Concepts

Ionic Compounds

• Typically have a metal as the cation.
• Can have a polyatomic ion like ammonium as the cation.

Types of Metals

1. Fixed Charge Metals (Type One Metals)

   • Charge is always the same.
   • Includes:
     • Group 1 Metals (e.g., Lithium, Sodium, Potassium) - all 1+ charge.
     • Group 2 Metals (e.g., Beryllium, Magnesium, Calcium) - all 2+ charge.
     • "Magic Triangle" Metals:
       • Aluminum, Gallium, Indium - 3+
       • Zinc, Cium - 2+
       • Silver - 1+

2. Variable Charge Metals (Type Two Metals)

   • Charge can vary (e.g., Iron can be 2+ or 3+).
   • Not in Group 1, Group 2, or the Magic Triangle.

Naming Variable Charge Metals

• Use Roman numerals to indicate the charge (e.g., Iron(II), Iron(III)).

Determining Charges in Ionic Compounds

• Balance of Charges: Total positive and negative charges must balance.
• Example: Cobalt with Nitrogen
  • Cobalt can have a variable charge; use the charge of the anion to determine.
  • Nitrogen (Nitride) is 3-.
  • Two nitride ions = 6- total; therefore, Cobalt must be 6+ total.
  • Three Cobalt ions must each be 2+ (Cobalt(II) Nitride).

Examples and Practice

1. Mercury Sulfide (HgS)

   • Mercury is not in fixed charge categories; thus, it has a variable charge.
   • Sulfide (from Sulfur) is 2-.
   • Mercury must be 2+ (Mercury(II) Sulfide).

2. Iron Nitrate (Fe(NO3)3)

   • Iron has a variable charge.
   • Nitrate is 1-. Three nitrates = 3- total.
   • Iron must be 3+ (Iron(III) Nitrate).

3. Magnesium Fluoride (MgF2)

   • Magnesium is in Group 2, fixed at 2+.
   • Fluoride is 1-. Two fluorides = 2- total.
   • Balance with magnesium (Magnesium Fluoride).

4. Tin Cyanide (Sn(CN)4)

   • Tin has a variable charge.
   • Cyanide is 1-. Four cyanides = 4- total.
   • Tin must be 4+ (Tin(IV) Cyanide).

5. Copper Oxide (Cu2O)

   • Copper has a variable charge.
   • Oxide is 2-.
   • Two copper ions must each be 1+ (Copper(I) Oxide).

6. Zinc Hyposulfite (ZnSO2)

   • Zinc is in the Magic Triangle, always 2+.
   • Hyposulfite is 2-.
   • Balance with zinc (Zinc Hyposulfite).

7. Chromium Phosphite (CrP3)

   • Chromium has a variable charge.
   • Phosphite is 3-. Two phosphites = 6- total.
   • One chromium ion must be 6+ (Chromium(VI) Phosphite).

Conclusion

• For more practice problems, refer to the additional resources provided by GetChemistryHelp.com.
• Emphasized the importance of understanding the balance of charges in naming ionic compounds.