Key Points on VOS Metals and Oxidation Numbers

Overview of VOS and Non-VOS Metals

  • VOS metals have variable oxidation states (need to memorize charges).
  • Non-VOS metals have set charges indicated on the periodic table.
  • Example naming convention includes Roman numerals to indicate charge of VOS metals.

Naming Ionic Compounds

  • Charges in ionic compounds must balance out to zero.
  • Process for finding the charge on a VOS metal involves:
    • Identify the metal and anion.
    • Set up an equation ensuring total charge equals zero.
    • Solve for the charge of the metal.
  • Example: Nickel II acetate gives nickel a charge of +2.

Oxidation Number Calculation

  • For compounds, oxidation numbers are calculated as follows:
    1. Identify each element's quantity.
    2. Set up an equation where the sum equals the total charge.
    3. Use known oxidation states:
    • Oxygen often = -2.
    • Fluorine = -1.
    • Hydrogen = +1 (check context).
  • Nonmetals generally seek to have an oxidation number based on their periodic group placement.

General Steps for Determining Oxidation Numbers

  1. Check for Neutral Elements: If neutral, oxidation number = 0.
  2. Set Up the Equation: For compounds, count elements and balance charges.
  3. Identify Non-VOS Metals: Apply set charges for non-VOS metals.
  4. Account for Nonmetals with Group Rules: Follow the order: fluorine, then hydrogen, oxygen last.

Special Considerations

  • Oxidation numbers may not equal charges in covalent compounds.
  • Understanding electronegativity can help when comparing charges among nonmetals.
  • Differentiate between oxidation states and standard charges (especially in complex ions).