Inorganic
Nomenclature:
The Cold Hard Truth
Adam Paltrineri
Chris Love
Chem. 324 Period A
March 2002
Inorganic Nomenclature: The Cold Hard Truth
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Naming Simple Cations:
Note: A cation is a positively charged ion.
Rule: Take the name of the element and add the word “ion”.
Example:
H+ = hydrogen ion
Mg2+ = magnesium ion
Ra2+ = radium ion
Naming Variable Valence Cations:
Note: There are only 5 elements that need concern us at this juncture – their charges are
listed in the following table:
Charge
Mercury
Copper
Iron
Tin
Lead
1+
Hg22+
Cu+
2+
Hg2+
Cu2+
Fe2+
Sn2+
Pb2+
3+
4+
Fe3+
Sn4+
Pb4+
Rule:
Stock Method:
Take the element name and add the Roman numeral equivalent of the positive charge
after the name and before the word “ion”.
Example:
Cu+ = copper(I) ion
Cu2+ = copper(II) ion
Rule: Classical Method:
• For the element with the lower positive charge: take the Latin root of the element
name and add “ous” then the word “ion”.
• For the element with the higher positive charge: take the root of the element name
and add “ic” then the word “ion”.
Example:
Cu+ = cuprous ion
Cu2+ = cupric ion
Naming Complex Cations:
Note: A complex cation is a polyatomic ion where more cations are present than ions.
Rule: There are special names for each complex cation – such as ammonium and hydronium –
add the word “ion” to the end of each.
Example:
NH4+ = ammonium
Naming Simple Anions:
Note: An anion is a negatively charged ion.
Rule: Take the stem of the element name then add the suffix “ide” and the word “ion”.
Example:
S3- = sulfide ion
Cl- = chloride ion
O2- = oxide ion
Naming Polyatomic Anions:
Note: The 10 most common polyatomic anions (including ammonium) that are necessary to
know are given on the following table:
Inorganic Nomenclature: The Cold Hard Truth
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Charge
1+
Anion
NH4+
“
“
“
“
Note: NH4+ is ammonium.
Note: OH- is hydroxide.
Note: CN- is cyanide.
Note: C2HgO2- is acetate.
Rule:
Polyatomic Ions
3PO43-
2SO42CO32CrO42-
- 2
1NO3ClO3C2HgO2OHCN-
• The most common compound has the suffix “ate” after the root of the non-oxygen
element followed by the word “ion”.
• The compound with one less oxygen atom than the most common has the suffix “ite”
after the root of the non-oxygen element followed by the word “ion”.
• The compound with two fewer oxygen than the most common has the prefix “hypo”
prior to the name of the non-oxygen element, the suffix “ite” on the end, then the
word “ion” after it.
• The compound with one more oxygen than the most common has the prefix “per”
before the root of the non-oxygen element, the suffix “ate” after the root and the
word “ion” tacked on for good measure.
• When hydrogen is present – add “hydrogen” or “bi” before the name.
ClO- = hyopchlorite ion
NO- = hyponitrite ion
ClO2 = chlorite ion
NO2- = nitrite ion
ClO3 = chlorate ion
NO3- = nitrate ion
ClO4 = perchlorate ion
NO4- = pernitrate ion
HSO4 = “hydrogen sulfate ion” or “bisulfate ion”.
When a Sulfur ion replaces an Oxygen ion in the most common form of an ion, add
“thio-” before the name:
• S2O32- = “thiosulfate”
• SCN- = “thiocyanate”
Examples:
Note:
Naming Simple Binary Salts:
Note: A simple binary salt is an ionic compound which results from the combination of a base
and an acid (minus the H2O that results as well)
Rule: Take the name of the base (the cation) followed by the root of the acid (the anion) plus
the ending “ide”.
Examples:
HCl (acid) + NaOH (base) = H2O and NaCl or “sodium chloride”.
HF + KOH = H2O and FK or “fluorine potasside”.
Naming Binary Salts With Variable Valence Metals:
Rule:
Stock Method:
Take the name of the salt and add the oxidation number of the base in roman numerals
after the name of the base.
Examples:
IK is “iodine(I) potasside”.
IK5 is “iodine(V) potasside”.
Rule: Classical (Descriptive) Method:
Take the name of the salt and add the suffix “ous” to the base name to the salt with
the lower oxidation number, or the suffix “ic” to the base name of the salt with the
higher oxidation number.
Examples:
• IK is “iodous potasside”.
• IK5 is “iodic potasside”.
Inorganic Nomenclature: The Cold Hard Truth
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Naming Ternary Salts:
Note:
A ternary salt is a salt with three elements in it’s composition - a polyatomic anion and
a metal cation.
Rule: Take the name of the first element and add the name of the polyatomic anion after it.
Examples:
• Na2SO4 = “sodium sulfate”
• K2CO3 = “potassium carbonate”
• NH2S = “nitrogen sulfate”
• Al(NO3)3 = “aluminum nitrate”
• Ca3(PO4)2 = “calcium potassate”
• (NH4)2C2O4 = “nitrogen carbonate”
• FeSO = “iron(III) sulfate”
• CuS = “cupric sulfate”
• Cu2S = “cuprous sulfate”
• Mg2N = “magnesium nitrate”
• K2SO3 = “potassium sulfite”
• K2CO4 = “potassium hypochlorate”
Naming Acid Salts:
Note:
Rule:
An acid salt is a salt containing more than one cation as well as hydrogen.
Use the name of the salt plus the word “hydrogen” between the base name and the
acid name. If more than one hydrogen is present, it may be necessary to add a
descriptive prefix to the word “hydrogen”.
Examples:
• Na3PO4 is a salt, “sodium potassate”, Na2HPO4 is an acid salt = “sodium
hydrogen phosphate”
• Na2SO4 is a salt, “sodium sulfate”, NaHSO4 is an acid salt = “sodium hydrogen
sulfate”
Naming Simple Bases:
Note: A base is an ionic compound of a metal ion and a hydroxide (OH-) ion.
Rule: Take the name of the metal ion and add the word “hydroxide”.
Example:
• NaOH = “sodium hydroxide”
• KOH = “potassium hydroxide”
• Ca(OH)2 = “calcium hydroxide”
Naming Variable Valence Bases:
Rule:
Stock Method:
Take the name of the metal ion and add the oxidation charge of the metal (in Roman
numerals in parenthesis) after the metal ion name. Then add the word “hydroxide”.
Example:
• Fe(OH)2 = “iron(II) hydroxide”
• Fe(OH)3 = “iron(III) hydroxide”
• Sn(OH)2 = “tin(II) hydroxide”
• Sn(OH)4 = “tin(IV) hydroxide”
Rule: Classical Method:
Take the name of the metal ion and add the suffix “ous” to the metal name of the base
with the lower oxidation number, or the suffix “ic” to the metal name of the base with
the higher oxidation number. Then add the word “hydroxide” for kicks.
Example:
• Fe(OH)2 = “ferrous hydroxide”
• Fe(OH)3 = “ferric hydroxide”
• Sn(OH)2 = “stannous hydroxide”
• Sn(OH)4 = “stannic hydroxide”
Naming Simple Metal Oxides:
Note:
Rule:
A metal oxide is an ionic compound of a metal and oxygen.
Take the name of the metal ion and add the word “oxide” or “peroxide” in the 4
special cases.
Examples:
• Na2O = “sodium oxide”
• K2O = “potassium oxide”
• Al2O3 = “aluminum oxide”
The 4 “peroxides”
• K2O2 = “potassium peroxide”
• H2O2 = “hydrogen peroxide”
• Na2O2 = “sodium peroxide”
• BaO2 = “barium peroxide”
Inorganic Nomenclature: The Cold Hard Truth
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Naming Variable Valence Metal Oxides:
Rule:
Stock Method:
Take the name of the metal ion and add the oxidation charge of the metal (in Roman
numerals in parenthesis) after the metal ion name. Then add the word “oxide”.
Example:
• FeO = “iron(II) oxide”
• Fe2O3 = “iron(III) oxide”
• PbO = “lead(II) oxide”
• PbO2 = “lead(IV) oxide”
Rule: Classical Method:
Take the name of the metal ion and add the suffix “ous” to the metal name of the base
with the lower oxidation number, or the suffix “ic” to the metal name of the base with
the higher oxidation number. Then add the word “oxide”.
Example:
• FeO = “ferrous oxide”
• Fe2O3 = “ferric oxide”
• PbO = “plumbous oxide”
• PbO2 = “stannic oxide”
Naming Nonmetal/Nonmetal Compounds:
Rule:
Stock Method:
Take the name of the first nonmetal and add the root of the second nonmetal plus the
suffix “ide”. If necessary, add the oxidation charge of the first nonmetal in Roman
numerals after the first nonmetal name.
Example:
• ClF = “chlorine fluoride”
• BI3 = “boron iodide”
• IF5 = “iodine(V) fluoride”
• IF7 = “iodine(VII) fluoride”
Rule: Descriptive Method:
State the first nonmetal, then take the root of the second nonmetal and add the suffix
“ide”. Add a Latin numeric prefix (see below) to either or both of the nonmetal names
to describe how many of each are present in the compound.
Prefixes:
“mono” – 1
“hexa” – 6
“di” – 2
“hepta” – 7
Example:
• ClF = “chlorine fluoride”
• BI3 = “boron tri-iodide”
• IF5 = “pentaiodine fluoride”
“tri” – 3
“octa” – 8
“tetra” – 4
“nona” – 9
“penta” – 5
“deca” – 10
• IF7 = “heptaiodine fluoride”
Naming Nonmetal Oxides:
Note:
Rule:
A nonmetal oxide is an ionic compound with a nonmetal and oxygen.
Stock Method:
Take the name of the first nonmetal and add the word “oxide”. If necessary, add the
oxidation charge of the first nonmetal in Roman numerals after the first nonmetal
name.
Example:
• KrO = “krypton oxide”
• B2O3 = “boron oxide”
• SeO2 = “selenium(IV) oxide”
• SeO3 = “selenium(VI) oxide”
Rule: Descriptive Method:
State the first nonmetal then add the word “oxide”. Add a Latin numeric prefix to
either the nonmetal or “oxide” to describe how many of each are present in the
compound.
• KrO = “krypton oxide”
• B2O3 = “diboron trioxide”
• SeO2 = “selenium dioxide”
• SeO3 = “selenium trioxide”
Inorganic Nomenclature: The Cold Hard Truth
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Naming Acids:
Note:
An acid is a molecular compound with a hydrogen (H+) that “leads off” the compound
and one or more nonmetals. The nonmetals are polyatomic anions in ternary acids.
Acids ionize in water (an H+ comes off).
Simple Acids:
Rule:
Take the root of the name of the anion and add the prefix “hydro” and the suffix “ic”
and the word “acid”.
Examples:
• HCl = “hydrochloric acid”
• HBr = “hydrobromic acid”
• HI = “hydroiodic acid”
• HCN = “hydrocyanic acid”
Ternary Acids:
Rule:
• Take the name of the most common polyatomic anion and substitute “ic” for “ate”
and add the word “acid”.
• Take the name of the polyatomic anion with “-ite” and substitute “ous” for “ite”
and add the word “acid”.
• Take the name of the “per- -ate” polyatomic anion and substitute “per- -ic” for
“per- -ate” and add the word “acid”.
• Take the name of the “hypo- -ite” polyatomic anion and substitute “hypo- -ous” for
“hypo- -ite” and add the word “acid”.
Examples:
• ClO3- (“chlorate”) plus an H+ = HclO3 (“chloric acid”)
• ClO2- (“chlorite”) plus an H+ = HclO2 (“chlorous acid”)
• ClO4- (“perchlorate”) plus an H+ = HclO4 (“perchloric acid”)
• ClO- (“hypochlorite”) plus an H+ = HclO (“hypochlorous acid”)
Naming Hydrates:
Rule:
Take the name of the compound and add the appropriate numerical descriptive prefix
to the word “hydrate” at the end.
Examples:
• MgSO4 = magnesium sulfate heptahydrate
• CaSO4 = calcium sulfate dihydrate
• Na2CO3 = sodium carbonate decahydrate.