Nomenclature Worksheet Notes: Simple Binary Ionic Compounds and Polyatomic Ions

Simple Binary Ionic Compounds (Worksheet 2)

  • Name of Ionic Compound — Formula

  • 1. Sodium bromide — \mathrm{NaBr}

  • 2. Calcium chloride — \mathrm{CaCl_2}

  • 3. Magnesium sulfide — \mathrm{MgS}

  • 4. Aluminum oxide — \mathrm{Al2O3}

  • 5. Lithium phosphide — \mathrm{Li_3P}

  • 6. Cesium nitride — \mathrm{Cs_3N}

  • 7. Potassium iodide — \mathrm{KI}

  • 8. Barium fluoride — \mathrm{BaF_2}

  • 9. Rubidium nitride — \mathrm{Rb_3N}

    1. Barium oxide — \mathrm{BaO}
    1. Potassium oxide — \mathrm{K_2O}
    1. Magnesium iodide — \mathrm{MgI_2}
    1. Aluminium chloride — \mathrm{AlCl_3}
    1. Calcium bromide — \mathrm{CaBr_2}
    1. Sodium nitride — \mathrm{Na_3N}
    1. Lithium fluoride — \mathrm{LiF}
    1. Barium phosphide — \mathrm{Ba3P2}
    1. Cesium sulfide — \mathrm{Cs_2S}
    1. Strontium fluoride — \mathrm{SrF_2}
    1. Sodium chloride — \mathrm{NaCl}

  • Notes on how to read these names and formulas:

    • In binary ionic compounds, a metal cation combines with a nonmetal anion.
    • The overall charge must balance to zero; subscripts show the relative numbers of ions.
    • When the metal forms only one common oxidation state (e.g., Group 1 elements, Group 2 elements, Aluminum), the cation charge is implied by the name.
    • For metals with multiple oxidation states, the oxidation state is named in parentheses after the metal (e.g., iron(II) oxide, iron(III) oxide). This is not needed for the specific set above since the metals shown have fixed common charges.

Ionic Compounds Containing Polyatomic Ions (Worksheet 3)

  • Name of Ionic Compound — Formula of Ionic Compound
  • 1. Sodium chromate — \mathrm{Na2CrO4}
    • Notes: Chromate is a polyatomic anion with formula \mathrm{CrO_4^{2-}}; the compound balances with two sodium ions.
  • 2. Calcium carbonate — \mathrm{CaCO_3}
    • Notes: Carbonate is a polyatomic anion with formula \mathrm{CO_3^{2-}}; the compound balances with one calcium ion.

Quick Reference: Key Rules for Naming and Formulas

  • Binary ionic compounds (two elements): cation name + anion name, with subscripts to balance charges.
    • Example: Sodium bromide uses cation Na^+ and anion Br^- → formula \mathrm{NaBr}.
  • For ions with fixed charges (most main-group elements in this set), no Roman numeral is needed.
  • For polyatomic ions, treat the polyatomic unit as the anion.
    • Example: Chromate (CrO4^{2-}) combines with Na^+ to form \mathrm{Na2CrO_4}.
  • Subscripts are determined to achieve overall neutrality: sum of positive charges equals sum of negative charges.
  • Common polyatomic ions used in practice (from given examples): chromate (CrO4^{2-}), carbonate (CO3^{2-}); these determine formulas like \mathrm{Na2CrO4} and \mathrm{CaCO_3}.

Connections to Foundational Principles

  • Ionic bonding: Transfer of electrons from a metal to a nonmetal to form cations and anions; electrostatic attraction holds the compound together.
  • Formula units reflect charge balance; subscripts indicate the smallest whole-number ratio of ions in the lattice.
  • Polyatomic ions act as a single unit with a fixed charge, which simplifies naming and formula derivation for compounds containing them.

Practical Implications and Real-World Relevance

  • Accurate naming and formula writing are essential for communicating chemical composition in labs, industry, and safety data.
  • Understanding polyatomic ions enables quick recognition of common reagents (e.g., chromate, carbonate) and their expected behavior in reactions.
  • Misnaming or incorrect formulas can lead to incorrect stoichiometry in reactions and potential safety hazards.

Quick Practice Questions (from Transcript material)

  • Give the formula for sodium chloride: \mathrm{NaCl}
  • Give the formula for calcium oxide (from the listing): \mathrm{CaO}
  • Give the formula for strontium fluoride: \mathrm{SrF_2}
  • Give the formula for calcium carbonate: \mathrm{CaCO_3}

(Note: The transcript contains specific itemized pairs for binary ionic compounds and a subset of polyatomic-ion compounds. The above notes reproduce those items with correct conventional formulas and LaTeX-formatted representations.)