Naming Compounds (Review)

Ionic Compounds (Simple)

    Recognizing Simple Ionic Compounds

  • The first element is always a metal (e.g. Na)
  • The second element is always a nonmetal (e.g. Cl)
  • Example: NaCl

    Naming Simple Ionic Compounds

  • 1. Take the name of the metal and keep it the same (e.g. Al → Aluminum)
  • 2. Take the name of the nonmetal and replace the ending with -ide (e.g. O → Oxygen → Oxide)
  • Example: Al2O3 → Aluminum Oxide
    • Note that the subscripts for the elements do not affect the name

    Formulas for Simple Ionic Compounds

  • 1. Find the valence charge of the metal (e.g. Magnesium → 2+)
  • 2. Find the valence charge of the nonmetal (e.g. Oxide → Oxygen → 2-)
  • 3. "Cross" the charges so the charge of one element becomes the subscript of the other (e.g. Mg2+ ↘ O2 and O2- ↘ Mg2)
  • 4. Reduce the subscripts to lowest terms (same ratio), and remove any 1s (e.g. Mg2O2 → Mg1O1 → MgO)
  • Example: Magnesium Oxide → MgO

Ionic Compounds (Multivalent)

    Recognizing Multivalent Ionic Compounds

  • The first element is always a metal which can have multiple valence charges (e.g. Fe)
  • The second element is always a nonmetal (e.g. O)
  • Examples: FeO (Fe2+), Fe2O3 (Fe3+)

    Naming Multivalent Ionic Compounds

  • 1. Take the formula and "uncross" the charges (e.g. SnO2 → Sn1O2 → Sn2+O1-)
  • 2. If the nonmetal has the wrong valence charge, multiply both charges by the same factor so they become correct (e.g. Oxygen is O2-, Sn2+O1- → Sn4+O2-)
  • 3. Take the name of the metal and add Roman numerals corresponding to its valence charge (e.g. Sn4+ → Tin (IV))
  • 4. Take the name of the nonmetal and replace the ending with -ide (e.g. O → Oxygen → Oxide)
  • Example: SnO2 → Tin (IV) Oxide
    • Note that the subscripts for the elements do affect the name

    Formulas for Multivalent Ionic Compounds

  • 1. Find the valence charge of the metal using Roman numerals (e.g. Iron (III) → 3+)
  • 2. Find the valence charge of the nonmetal (e.g. Bromide → Bromine → 1-)
  • 3. "Cross" the charges so the charge of one element becomes the subscript of the other (e.g. Fe3+ ↘ Br3 and Br1- ↘ Fe1)
  • 4. Reduce the subscripts to lowest terms (same ratio), and remove any 1s (e.g. Fe1Br3 → FeBr3)
  • Example: Iron (III) Bromide → FeBr3

Ionic Compounds (Polyatomic)

    Recognizing Polyatomic Ionic Compounds

  • The first element is either a metal (e.g. K) or a polyatomic cation (NH4)
  • The next element(s) is either a polyatomic anion (e.g. OH) or a single nonmetal (e.g. F)
  • Examples: KOH, NH4F

    Some Common Polyatomic Ions That You Should Know:

  • Ammonium – NH4+
  • Acetate – C2H3O2-
  • Hydroxide – OH-
  • Carbonate – CO32-
  • Hydrogen Carbonate – HCO3-
  • Nitrate – NO3-
  • Sulfate – SO42-
  • Phosphate – PO43-

    Naming Polyatomic Ionic Compounds

  • 1. Take the name of the metal or polyatomic cation and keep it the same (e.g. Na → Sodium)
    • If the metal is multivalent, it will need to be named using Roman numerals
  • 2. Take the name of the polyatomic anion and keep it the same (e.g. CO3 → Carbonate)
    • If there is a single nonmetal instead of a polyatomic anion, replace its ending with -ide
  • Examples: Na2CO3 → Sodium Carbonate, NH4F → Ammonium Fluoride

    Formulas for Polyatomic Ionic Compounds

  • 1. Find the valence charge of the metal/polyatomic cation (e.g. Calcium → 2+)
  • 2. Find the valence charge of the polyatomic anion/single nonmetal (e.g. Acetate → 1-)
  • 3. "Cross" the charges so the charge of one ion becomes the subscript of the other (e.g. Ca2+ ↘ (C2H3O2)2 and C2H3O21- ↘ Ca1)
    • When applying a subscript to a polyatomic ion, put the ion in brackets first
  • 4. Reduce the subscripts to lowest terms (same ratio), and remove any 1s (e.g. Ca1(C2H3O2)2 → Ca(C2H3O2)2)
  • Example: Calcium Acetate → Ca(C2H3O2)2

Covalent Compounds

    Recognizing Covalent Compounds

  • The first element is either a nonmetal (e.g. C) or metalloid (e.g. Si)
  • The second element is either a nonmetal (e.g. O) or metalloid (e.g. B)
  • Examples: CO2, SiO2

    Naming Covalent Compounds

  • 1. Take the name of the first element and add a prefix if its subscript is greater than 1 (e.g. N2 → Dinitrogen)
  • 2. Take the name of the second element, add a prefix, and replace the ending with -ide (e.g. O4 → Tetroxide)
    • Note that the last "a" or "o" of prefixes is often omitted when followed by an "a" or "o" (tetraoxide → tetroxide)
  • Examples: N2O4 → Dinitrogen Tetroxide, CO → Carbon Monoxide
    • Note that the subscripts for covalent compounds are never reduced to lowest terms

    Prefixes for up to Six Atoms

  • 1 – Mono
  • 2 – Di
  • 3 – Tri
  • 4 – Tetra
  • 5 – Penta
  • 6 – Hexa

    Formulas for Covalent Compounds

  • 1. Determine the subscript of the first element using its prefix (e.g. Dihydrogen → H2)
  • 2. Determine the subscript of the second element using its prefix (e.g. Monosulfide → S1)
  • 3. Remove any 1s from the subscripts (e.g. H2S1 → H2S)
  • Examples: Dihydrogen Monosulfide → H2S, Silicon Dioxide → SiO2