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 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 its 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 its 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,
5. Stuff to memorize
Charges on Group 1, Group 2, and non-metals in Groups 13 - 17. Can
you explain why Group 18 is not included?
- Names of monatomic ions
Groups 1 and 2 are the same as the element name.
Non-metals are the root + -ide.
- Transition metals (inlcuding metals under the staircase) are the
element's name followed by the metal's charge in roman numerals in
Common names for some compounds (See the last point in #3)
|(there's also a list from
[Quickie naming Flow-Chart][Quickie
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