1. Introduction to Chemistry

2. The Periodic Table

3. Quantum Numbers

4. Electron Configuration

5. Chemical Families

6. Oxidation Numbers

7. Chemical Formulas

8. Chemical Names

9. Formula Mass

10. Percentage Composition

11. Reaction Types

12. Balancing Equations

13. The Mole Concept

14. Solution Concentration

15. Stoichiometry

16. Kinetic Theory

17. The Gas Laws

18. Enthalpy & Heat

19. Reaction Rates

20. Acids & Bases

21. pH Scale

22. Salts

23. Net Ionic Equations

24. Redox Reactions

25. Organic Chemistry

26. Nuclear Chemistry

8. Naming Chemical Formulas

Chemical Nomenclature

There are over 19 million known chemical substances. Without some type of system, naming these substances would be hopelessly complicated. The system used in naming substances is called chemical nomenclature.

There are two major divisions to the International Union of Pure and Applied Chemistry (IUPAC) system:

Organic compounds contain carbon, usually in combination with hydrogen, oxygen, nitrogen, and/or sulfur.

All other substances are inorganic compounds, divided into three basic categories:

  • ionic compounds
  • molecular compounds
  • acids
Naming inorganic compounds begins with naming ions.

Cations formed from metal atoms have the same name as the metal. See a chart of common cations

  • If - and ONLY if - a metal can form different cations, the positive charge is indicated by a Roman numeral in parentheses following the name of the metal.
    • Fe+2   iron (II)
    • Fe+3   iron (III)
The names of monatomic anions are formed by replacing the ending of the name of the element with -ide. See a chart of common anions.
  • Cl   chloride ion
  • Br   bromide ion
  • S−2   sulfide ion
Polyatomic ions     The short list     The long list
  • A few simple polyatomic anions also have names ending in -ide.
    • OH   hydroxide ion
    • CN   cyanide ion
  • Polyatomic cations formed from nonmetal atoms have names ending in -ium.
    • NH4+   ammonium ion
    • H3O+   hydronium ion
  • Polyatomic anions containing oxygen (oxyanions) have names ending in -ate or -ite.
    • The ending -ate is used for the most common oxyanion of an element.
      • NO3   nitrate ion
      • SO4−2   sulfate ion
    • The ending -ite is used for an oxyanion that has the same charge but one less oxygen atom.
      • NO2   nitrite ion
      • SO3−2   sulfite ion
    • Prefixes are used when the series of oxyanions of an element extends to four members:
      • The prefix per- indicates one more oxygen atom than the oxyanion ending in -ate.
        • ClO4   perchlorate ion
      • The prefix hypo- indicates one less oxygen atom than the oxyanion ending in -ite.
        • ClO   hypochlorite ion
  • Polyatomic anions derived by adding H+ to an oxyanion are named by adding as a prefix the word hydrogen or dihydrogen, as appropriate.
    • HCO3   hydrogen carbonate ion

Names of ionic compounds consist of the cation name followed by the anion name.

  • NaOH     sodium hydroxide
  • Al2(SO4)3     aluminum sulfate
  • CuS     copper (II) sulfide
Naming binary (two-element) molecular compounds is similar to naming ionic compounds.
  • The name of the element farther to the left on the periodic table is usually written first. Oxygen is an exception, always written last unless combining with fluorine.
  • If both elements are in the same group on the periodic table, the one having the higher atomic number is named first.
  • The name of the second element is given an -ide ending.
  • Greek prefixes (table below) are used to indicate the number of atoms of each element.

    The prefix mono- is NEVER used with the first element in the compound.

    molecule prefixes
Know the names and formulas for the "Big 3" industrial acids - hydrochloric acid, sulfuric acid, and nitric acid.

Organic compounds have their own system of nomenclature. It will be covered later in the organic chemistry section.

Chemical Nomenclature

Formulas and Names

Chemical Formulas and Names