NAMING BINARY, TERNARY, AND QUATERNARY COMPOUNDS

1. Binary Ionic Compounds (formula contains one metal and one nonmetal):

compound name = [cation name] [anion name]

Examples: Al2O3 aluminum oxide MgCl2 magnesium chloride Fe2O3 iron(III) oxide Fe2O3 ferric oxide CuCl2 cupric chloride CuCl cuprous chloride

2. Ternary and Quaternary Ionic Compounds (Monatomic Metal Cation with Polyatomic Anion, Polyatomic Cation with Polyatomic Anion, or Polyatomic Cation with Monatomic Nonmetal Anion):

compound name = [cation name] [anion name]

Examples: (NH4)2S ammonium sulfide Mg(CN)2 magnesium cyanide (NH4)2SO4 ammonium sulfate FeCO3 iron(II) carbonate Ca(NO3)2 calcium nitrate FeCO3 ferrous carbonate

3. Binary Covalent (Molecular) Compounds (formula contains two nonmetals):

The element listed first in the formula is the one closest to the left side and/or bottom of the periodic table (i.e., having the lowest electronegativity).

The element listed second in the formula is the one closest to the right side and/or top of the periodic table (i.e., having the highest electronegativity).

compound name = [numerical prefix* + first element name] [numerical prefix* + second element stem + -ide suffix]

# Atoms Prefix # Atoms Prefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca

*If the prefix for the first element name would be "mono", it is omitted. "Mono" is always included for the second element if there is only one atom of that element in a molecule. *If the either the first or second element name begins in a vowel, the last letter is dropped from prefixes ending in "a" or "o", but not from prefixes ending in "i".

Examples: N2O3 dinitrogen trioxide CO2 carbon dioxide (not monocarbon dioxide) N2O5 dinitrogen pentoxide CO carbon monoxide (not monocarbon monoxide) SCl4 sulfur tetrachloride IF7 iodine heptafluoride 4. Binary Acids (NOTE: Pure acids exist as covalently bonded molecules even though they form ions in

solution): Pure Compound: Name as if it were a ionic compound containing a hydrogen ion (H+) and an anion.

In Aqueous Solution: Compound Name = [hydro + element stem or name + ic] [acid]

Examples: Formula Pure Compound Aqueous Solution HF hydrogen fluoride hydrofluoric acid HCl hydrogen chloride hydrochloric acid HI hydrogen iodide hydroiodic acid H2S hydrogen sulfide hydrosulfuric acid 5. Common Names of Some Frequently Encountered Molecular Covalent Compounds:

CH4 methane NH3 ammonia CH3OH methanol C2H4 ethylene C2H6 ethane H2O water CH2O formaldehyde C2H2 acetylene

NAMING BINARY, TERNARY, AND QUATERNARY COMPOUNDS 6. Oxyacids (NOTE: Pure acids exist as covalently bonded molecules even though they form ions in

solution):

Pure Compound: Name as if it were a ionic compound containing a hydrogen ion (H+) and an anion.

In Aqueous Solution: Compound Name = [(element or anion name or stem) + (ous or ic)] [acid] Use "ous" for acid if anion name ends in "ite"; use "ic" for acid if anion name ends in "ate".

Examples: Formula Pure Compound Aqueous Solution HNO2 hydrogen nitrite* nitrous acid HNO3 hydrogen nitrate nitric acid H2SO4 hydrogen sulfate sulfuric acid H2SO3 hydrogen sulfite* sulfurous acid HC2H3O2 hydrogen acetate acetic acid H3PO4 hydrogen phosphate phosphoric acid

*These compounds are not stable in pure form. They exist only in solution