Nomenclature means "naming system."  Since this is a system of naming chemicals, it is supposed to be easy to remember.  There is a minimum of memorizing needed to name hundreds of chemicals.  You will need a periodic table.  It will not be possible to pass the Nomenclature Test without knowing both sides of this sheet inside and out. Click here to see what procrastinating feels like!

1. Group 1 or Group 2 metals + non-metals

• The positive and negative ions only have one possible charge each (sodium is always +1) so there is no need to hint what the charges are in the name.  Therefore, these are the simplest to name.
• The name of the compound is [metal's name] + [non-metal root] + [ide].  So sodium + chlorine becomes sodium chloride, calcium + sulfur becomes calcium sulfide, etc.
• The metals always goes first.  If there is more than one metal, just list them in the name.  NaKS would be sodium potassium sulfide.
• NH4⁺ gets treated exactly like a Group 1 metal.  NH4Cl is ammonium chloride.
• Polyatomic anions (negative ions) get treated exactly like non-metals, except they don't get changed over to -ide form.  KNO3 is potassium nitrate.

2. Transition metals or metals under the staircase + non-metals

• Transition metals usually have more than one possible charge (iron can commonly be 2+ or 3+).  This means that the names have to include a hint of which charge the metal seems to have.  This is the roman numeral.
• The metal always goes first.  The name of the compound is [name of metal] + [(roman numeral)] + [non-metal root] + [ide].  The oxidation number (charge) on the metal goes in the parentheses.  FeCl2 is iron (II) chloride, and FeCl3 is iron (III) chloride, and FeO is iron (II) oxide.
• You may need to work backwards from the formula to find the charge on the metal.  In Os2S3, osmium could have any charge, but sulfur has a 2– charge.  Since there are three sulfurs (for a total of 6–), each osmium must have a 3+ (for a total of 6+).  This would be osmium (III) sulfide.
• Rules for order of listing are the same as in #1.

3. Two non-metals

• Preferred Method
  • Name compounds of two non-metals as in #2.  The atom closest to the metals gets the roman numeral.  N2O5 would be nitrogen (V) oxide.
• Acceptable Alternate Method
• A Greek prefix must be used for each element listed.  The only exception is when there is only one atom of the first element listed.  CO is carbon monoxide, CO2 is carbon dioxide, and N2O3 is dinitrogen trioxide.
• The compounds are named as in #1, except the element furthest left and down on the periodic table is listed first.  SF2 is sulfur difluoride.
• Some compounds have optional "common names."  For example, H2O (water), NH3 (ammonia), CH4 (methane), and O3 (ozone).
• Hydrocarbons - see table 7.12 in the book.  We will only focus on "straight chain" hydrocarbons with only single bonds.

4. Oxyacids (hydrogen attached to a polyatomic anion containing oxygen)

• If the polyatomic ion ends in -ate then the name of the compound is the root + “-ic acid.”   H2SO4 is hydrogen + sulfate, so it’s sulfuric acid.
• One more oxygen on an ion than the -ate form is the per-root-ate.  Chlorate is ClO3^– so ClO4^– is perchlorate.  Since HClO3 is chloric acid, then HClO4 is perchloric acid.
• If the polyatomic ion ends in -ite then the name of the compound is the root + “-ous acid.”   H2SO3 is hydrogen + sulfite, so it’s sulfurous acid.  Note that sulfite has one less oxygen atom than sulfate.
• One less oxygen on an ion than the -ite form is the hypo-root-ite.  Chlorite is ClO2^– so ClO^– is hypochlorite.  Since HClO2 is chlorous acid, then HClO is hypochlorous acid.
• Note:  Hydrogen + a non-metal makes a binary acid.  These are named hydro- + non-metal root + -ic acid.  HCl is hydrochloric acid (compare to chloric acid above), HF is hydrofluoric acid, etc.

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