How To Name Ionic Compounds In Chemistry

Definition of Compounds

  • Compound: A substance that is composed of two different elements.

  • Example: Na (sodium) + Cl (chlorine) = NaCl (sodium chloride).

Ionic Compounds

  • Ionic Compounds: Composed of ions including cations (positively charged) and anions (negatively charged).

  • When naming an anion, change the ending from "ine" to "ide".

  • Example: NaCl is named sodium chloride.

Naming Ionic Compounds

  1. Name the first element (cation).

    • Example: Mg (magnesium).

  2. Name the second element (anion) and change the ending to "ide".

    • Example: MgBr2 = magnesium bromide (Br becomes bromide).

Additional Examples

  • CaO: Ca (calcium) + O (oxygen) = calcium oxide.

  • AlP: Al (aluminum) + P (phosphorus) = aluminum phosphide.

Polyatomic Ions

  • Familiar polyatomic ions include:

    • NO3^- = nitrate

    • NO2^- = nitrite

    • PO4^3- = phosphate

    • PO3^3- = phosphite

    • SO4^2- = sulfate

    • SO3^2- = sulfite

    • OH^- = hydroxide

    • CN^- = cyanide

    • CrO4^2- = chromate

    • Cr2O7^2- = dichromate

Naming Ionic Compounds with Polyatomic Ions

  1. Example: K3NO3 = potassium nitrate (K = potassium, NO3^- = nitrate).

  2. Example: CaSO4 = calcium sulfate (Ca = calcium, SO4^2- = sulfate).

Transition Metals

  • For transition metals, indicate the charge in the name with Roman numerals:

    • Example: FeCl2 = iron(II) chloride (Fe^2+).

    • FeCl3 = iron(III) chloride (Fe^3+).

Naming Examples for Sulfide Compounds

  • Example: CuS = copper sulfide. Determine the charge of copper:

    • Sulfur (S) has a -2 charge; hence, copper must be +2 (Cu^2+), resulting in copper(II) sulfide.

  • Example: Cu2S = copper(I) sulfide.

    • Cu must be +1 to balance with -2 charge from sulfur.

Summary Instructions

  • Practice naming ionic compounds regularly to improve understanding.