NOMENCLATURE: Chemical Names

  • For Naming Compounds, the rules are divided by type of bonding.
    1. Ions
    2. Ionic Compounds (Metal + Nonmetal)
    3. Covalent Compounds (Nonmetal + Nonmetal) (H+ Nonmetal)

·          Accepted common names:
Water - H2O and Ammonia - NH3

  1. ION NOMENCLATURE:

CATIONS: Metal Ions and Polyatomic Ions

Group 1A , 2A, & Al Cations
Name the element + "ion"; the charge is equal to the Group #
Ex. Na+ is Sodium ion and Aluminum ion is Al3+

Transition Metals and Post-Transition Metal Cations
Name the element w/ charge as (Roman Numeral) + "ion"
Charge has to be given or derived from the formula
Ex. Fe3+ is iron(III) ion or from name: tin(II) is Sn2+

Polyatomic Cations
NH4+ (ammonium ion) & H3O+ (hydronium ion)


ANIONS:

Group 5A, 6A, & 7A Anions
Name root of element and add -ide suffix + "ion"
Charge is equal to Group # - 8
Ex. F- fluoride ion, sulfide ion S2 -

Polyatomic Anions – Table 2.5
These anions end in -ate suffix and must be memorized.
A few exceptions to the -ate suffix are : CN-, OH-, O22-

Oxyanions: Memorize base + -ate suffix + "ion" (Fig. 2.26)

If oxyanion w/ 1 more O than base, add per- prefix to ion
If oxyanion w/ 1 less O than base, change -ate to -ite
If oxyanion w/ 2 less O than base, change -ate to -ite and
add hypo- prefix to ion.

Ex. ClO3- chlorate ion (base) ClO4- perchlorate ion
ClO2- chlorite ion ClO- hypochlorite ion

 

  1. IONIC NOMENCLATURE:

Name the cation (w/out "ion") then anion (w/out "ion")
Use subscripts to conserve neutrality of compounds.

NaCl: Na+ (sodium ion) + Cl- (chloride ion)
Sodium chloride

Magnesium nitrate:
Magnesium ion (Mg2+) + Nitrate ion (NO3-)
Mg(NO3)2
(Needed 2 of -1 nitrate ions to balance +2 charge of magnesium ion)

  1. COVALENT NOMENCLATURE:

Name the first element, then the root of the second element + -ide suffix.
Designate the number of each element by using Greek prefixes as shown in Table 2-6.
e.g. mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona-, deca-

Ex.: SO2 sulfur dioxide CCl4 carbon tetrachloride
N2O5 dinitrogen pentaoxide

Acids: H + Nonmetal (or Polyatomic anion)
Binary Acids (H + one other type of atom):
Add prefix hydro- to the anion name and replace suffix -ide with -ic acid.
Ex.: HBr hydrobromic acid

Oxyacids: H+ Oxyanion
Replace the suffix -ate in the oxyanion name with -ic "acid" OR
replace the suffix -ite with -ous "acid".
** Keep any prefixes that went with the oxyanion name.
Ex.: HNO3 is nitric acid and HNO2 is nitrous acid
HClO4 is perchloric acid HClO is hypochlorous acid

  • HYDRATES:

Many ionic compounds also have water molecules incorporated into their crystalline structure. One can not predict the number of H2O's in a compound. These discrete water molecules are shown after the chemical formula by adding "· n H2O" to the formula.
In the name, the number of waters is designated by the Greek prefixes.

Ex. CuSO4•. 5H2O is Copper sulfate pentahydrate

THE ONLY WAY TO GET GOOD AT NOMENCLATURE IS

PRACTICE, PRACTICE, PRACTICE !!