Nomenclature of Ionic Compounds

Key Concepts

• Ionic Compounds: Compounds formed from ions, typically consisting of metals and nonmetals.
• Polyatomic Ions: Charged entities composed of several atoms.
• Transition Metals: Elements that can form multiple oxidation states.

Polyatomic Ions

• SO3 2-: Sulfite
• SO4 2-: Sulfate
• S2-: Sulfide (monatomic ion)
• PO4 3-: Phosphate
• PO3 3-: Phosphite
• P3-: Phosphide (monatomic ion)
• Chlorine-based ions:
  • ClO4-: Perchlorate
  • ClO3-: Chlorate
  • ClO2-: Chlorite
  • ClO-: Hypochlorite
  • Cl-: Chloride (monatomic ion)

Other Important Ions

• OH-: Hydroxide
• CO3 2-: Carbonate
• NO3-: Nitrate
• NO2-: Nitrite
• CH3COO-: Acetate
• CrO4 2-: Chromate
• Cr2O7 2-: Dichromate
• MnO4-: Permanganate
• CN-: Cyanide
• C2O4 2-: Oxalate

Naming Ionic Compounds

• Example 1: NaCl

  • Na: Sodium
  • Cl: Chloride
  • Compound name: Sodium chloride

• Example 2: KClO3

  • K: Potassium
  • ClO3: Chlorate
  • Compound name: Potassium chlorate

Transition Metals with Multiple Oxidation States

• Use Roman numerals to specify the oxidation state.

• Example: FeCl2 and FeCl3

  • FeCl2: Iron(II) chloride
  • FeCl3: Iron(III) chloride

Roman Numerals

• I = 1
• II = 2
• III = 3
• IV = 4
• V = 5
• VI = 6
• VII = 7

Determining Oxidation States

• Write an equation to solve for the oxidation state:
  • Fe in FeS:
    • S is -2; Fe must be +2 (Iron(II) sulfide)
  • Fe in Fe2S3:
    • S is -2, total is -6; Fe must be +3 (Iron(III) sulfide)

Monatomic Ion Charges

• Group 1 metals (e.g., Na, Li): +1
• Group 2 metals (e.g., Ca, Mg): +2
• Group 3A elements (e.g., Al, Ga): +3
• Group 4A elements (e.g., Si, Ge, Sn, Pb): +2 or +4
• Nitrogen and phosphorus: -3
• Chalcogens (e.g., O, S, Se): -2
• Halogens (e.g., F, Cl, Br, I): -1

Examples with Transition Metals

• PbO:

  • PbO: Lead(II) oxide

• PbO2:

  • PbO2: Lead(IV) oxide

• V3P5:

  • V is +5: Vanadium(V) phosphide

• Sn3(PO4)4:

  • Sn is +4: Tin(IV) phosphate

Conclusion

• Naming Ionic Compounds: Requires understanding of ion charges, particularly with transition metals and polyatomic ions.
• Transition Metals: Use Roman numerals for clarity in oxidation states.

By mastering these rules, you can accurately name and identify ionic compounds in various chemical contexts.