So…..What’s Really in a Name?
An Introduction to Chemical Nomenclature
Bill C. Ponder
Why is nomenclature important?
Innovation and discovery are born from the concentrated arrangement and dynamic review of
numerous and seemingly unrelated ideas. Genius or inspiration fuses these ideas into powerful new
creations of cultural and technological development. A multitude of representative examples, spanning
the last 5,500 years, are found in the areas of invention, art, literature, government, engineering,
science, music, philosophy, etc. However, the cultural and technological sophistication of humanity
remained decidedly stone-age for tens of thousands of years prior to 5,500 years ago1. The exchange
and accumulation of ideas during pre-history was severely restricted by spatial distance (human
populations were small and widely dispersed) and temporal distance (ideas that were not readily
adopted or widely disseminated died with their creators). With the development of a writing system
5,500 years ago, ideas generated at different locations and times could be collected and concentrated
into a common place and moment in the form of written text2. Interestingly, this time-point also marks
the beginning of humanity’s rapid cultural and technological advancement, and within a flash of time
relative to all the years previous (Figure 1)3, humans were transported from the stone-age to the current
“information” age. The invention of writing systems is perhaps the most significant occurrence in all of
human existence, outside of the development of spoken language – which leads to the next, very
obvious point – the existence of spoken language is a prerequisite for the development a writing
system2.
Figure 1. The invention of writing systems accelerated human development.
© Bill Ponder
What does any of this have to do with chemistry?
The descriptions, explanations and examples of this assignment comprise an introduction to chemical
nomenclature: the rules governing the spoken language (i.e. naming of compounds) and the writing
system of chemistry. These rules are used for effective communication, accumulation, review and
application of chemical knowledge. Applied chemistry is a primary contributor to the diversified array of
infrastructure (Table 1) associated with the modern world. Those fluent in speaking (naming) and
literate in the reading and writing of chemistry will certainly have an advantage as the frontier of
technological innovation moves forward.
Computing
Aerospace
Communication
microchip engineering and
manufacturing,
heat dissipation
high-performance lowmaintenance alloys and ceramics,
ultra-strong adhesives
fiber optic cables,
liquid crystal displays
Transportation
Commerce
Medicine
lightweight structural
composites,
long-lasting lubricants,
corrosion and scale inhibition
packaging materials,
high-speed printing and scanning,
identification counterfeit and
altered product
extended-release
pharmaceuticals,
targeted chemotherapeutics,
biocompatible surgical implants
Biotechnology
Construction
Energy
genome mapping,
engineering plastics,
photovoltaics (solar cells),
tissue regeneration,
high-strength low-density concrete,
bio-fuels manufacturing,
multiplex assays
high-efficiency thermal barriers
enhanced petroleum extraction
Table 1. Areas of modern infrastructure with specific examples where knowledge of chemistry is
particularly important.
At this level of study, you are probably already familiar with many of the names used in this exercise,
such as sodium, nitrogen, chlorine, phosphorous, magnesium and calcium. In addition, the meanings
you have developed for these names may be more nuanced than perhaps they were at the beginning of
the term. For example, the names above are no longer just “chemicals” but are “elements”, “a Group 1
metal”, “a halogen” or “elements with five valence electrons”. These subtleties reflect a growing
sophistication in your view of the world, and you need a way to express your view.
However, a group of names and meanings does not constitute a language. For example, the
arrangement of words - “tour history space in first” - is quite nonsensical, though each of the words is
familiar. Using generally accepted rules governing the arrangement of words relative to each other, the
phrase - “the first space tour in history” - conveys clear meaning. Therefore, the arrangement of words
also provides the framework (or context) within which the meanings of the words operate.
As you learn the language and writing system of chemistry, try to remember that chemical
nomenclature is far more than names for symbols and symbols for names. Focus on what the chemical
names and chemical formulas are telling you about atomic and molecular structure.
© Bill Ponder
The naming rules introduced within this laboratory exercise are maintained by the International Union
of Pure and Applied Chemistry (IUPAC) and can be found within “The Rules of Inorganic Nomenclature”
(also known as “The Red Book”), an IUPAC publication. More information can be found at
http://www.iupac.org/
Association of the names of elements to their respective symbols in the periodic table is a necessary
requirement for chemical literacy. The use of a periodic table containing both element names and
symbols is permissible for this assignment. However, periodic tables providing both element names and
symbols may not be available during quizzes or exams.
Assignment Definitions







Chemical Formula –written combinations of at least one symbol for an element, numbers and
other punctuation to indicate the relative amounts of elements comprising a chemical
compound or molecular element such as H2.
Ion – An electrically charged atom or molecule resulting from unequal numbers of electrons and
protons within the atom or molecule (e.g. Na+ or Cl-).
Polyatomic Ion – A molecule, usually composed of more than one element, and also possessing
either negative or positive charge (e.g. SO42-).
Cation – An ion possessing more protons than electrons (positively charged, e.g. Na+).
Anion – An ion possessing more electrons than protons (negatively charged, e.g. Cl-).
Oxidation State (also called oxidation number) – For atomic cations, describes the number of
electrons removed to produce the resulting cation.
Binary Compounds – Ionic compounds and covalent compounds composed of only two
elements (e.g. NaCl, H2O, PCl3, Al2O3). Binary compounds are further classified into Type I, Type II
and Type III binary compounds.
 Type I Binary Compounds – Ionic binary compounds containing metals that commonly
exhibit only one oxidation state. Calcium, for example, commonly exhibits only a 2+
oxidation state (Ca2+). Calcium is not found within compounds while possessing a 1+, 3+
or higher oxidation state. These metals are called Type I metals.
 Type II Binary Compounds – Ionic binary compounds containing metals that commonly
exhibit more than one oxidation state. For example, copper is commonly found in 1+
(Cu+) or 2+ (Cu2+) oxidation states. These metals are called Type II metals.
 Type III Binary Compounds – Binary covalent compounds containing two nonmetals (e.g.
HCl).
Type I Binary Compounds




The first part of the name will indicate the metal cation. The metal is ALWAYS the cation.
The second part of the name will indicate the anion. The anion’s name is derived by modifying
the ending of the element name with –ide. It is ALWAYS a nonmetal.
The group number of the cation will indicate its oxidation state (i.e. its charge). Cations are
formed by the loss of electrons. The loss of electrons will occur so that the resulting cation has 8
electrons in its outer (valence) shell which resembles a noble gas valence shell.
For anions, by subtracting 18 from the Group #, the charge can usually be calculated. Anions are
formed by gaining electrons, so that the resulting anion has a noble gas configuration.
© Bill Ponder

Within the chemical formula, cations and anions come together in such a way as to balance the
positive and negative charge. Therefore, the chemical formula represents the number of cations
and anions needed to result in no overall charge.
K has a 1+ charge,
Example:
S has a 2- charge
First part of name,
metal cation, Group 1,
1+ oxidation state
Second part of name and ends
with -ide, nonmetal anion,
Group 16, has charge of 2-
+
2-
Therefore two K are needed to balance one S
potassium sulfide……………………………………………………………………….K2S
Type II Binary Compounds






The first part of the name will indicate the metal cation. The metal is ALWAYS the cation.
Metals of Type II compounds can exhibit more than one oxidation state (see Assignment
Definitions). Hence, an unambiguous method of indicating the oxidation state of the metal
cation is needed. For example, both CuCl and CuCl2 are possible. They cannot both have the
name of “copper chloride”. Hence, CuCl is named copper(I) chloride and CuCl 2 is named
copper(II) chloride. The roman numeral indicates the oxidation state of the metal.
All of the metals in Groups 1 and 2 form Type I compounds. Except for Al, Ga, Zn, Cd and Ag, the
metals in Groups 3 through Groups 15 form Type II compounds.
The second part of the name will indicate the anion. The anion’s name is derived by modifying
the ending of the element name with –ide. It is ALWAYS a nonmetal.
For anions, by subtracting 18 from the Group #, the charge can usually be calculated. Anions are
formed by gaining electrons, so that the resulting anion has a noble gas configuration.
Within the chemical formula, cations and anions come together in such a way as to balance the
positive and negative charge. Therefore, the chemical formula represents the number of cations
and anions needed to result in no overall charge. (HINT: If the formula of a Type II compound is
given, the charge of anion will indicate the oxidation state of the Type II metal.)
Polyatomic Ions
A list of common polyatomic ions is given in Table 2. You will have to memorize the names, formulas and
charges associated with the polyatomic ions given in Table 2. Your instructor may require that you know
more than those provided on the list.
Ion Name
Ion
Formula
Ion
Charge
Ion Name
Ion
Formula
Ion
Charge
ammonium
NH4+
1+
perchlorate
ClO4-
1-
acetate
C2H3O2-
1-
dihydrogen phosphate
H2PO4-
1-
carbonate
CO32-
2-
hydroxide
OH-
1-
hydrogen carbonate*
HCO3-
1-
nitrate
NO3-
1-
chromate
CrO42-
2-
nitrite
NO2-
1-
cyanide
CN-
1-
phosphate
PO43-
3-
hypochlorite
ClO-
1-
sulfate
SO42-
2-
© Bill Ponder
chlorite
ClO2-
1-
chlorate
ClO3-
1-
sulfite
SO32-
2-
Table 2. A list of common polyatomic ions. *Hydrogen carbonate is commonly known as bicarbonate.
Naming Ionic Compounds Containing Polyatomic Ions





The first part of the name will indicate the cation.
If the cation is a Type I or Type II metal, name accordingly. If the cation is a polyatomic ion,
simply provide the name of the ion to the first part of the compound name.
The second part of the name will indicate the anion. If the anion is a polyatomic ion, simply
provide the name of the ion to the second part of the compound name.
Within the chemical formula, cations and anions come together in such a way as to balance the
positive and negative charge. Therefore, the chemical formula represents the number of cations
and anions needed to result in no overall charge.
The number of polyatomic ions needed to balance the overall charge in the formula is
determined in the same manner as atomic ions. If more than one polyatomic ion is needed,
parenthesis are placed around the entire polyatomic ion. For example, the chemical formula for
copper(II) nitrate is Cu(NO3)2. Compare this to copper(II) chloride – CuCl2. Both NO3- and Cl- have
1- charge. Therefore, two of each anion is need to balance the 2+ charge on Cu2+.
Type III Binary Compounds





These compounds are covalent compounds and almost never contain metals.
The first part of the name will indicate the least electronegative element and will also contain a
prefix (di-, tri-, tetra-, penta-, hexa-, octa-, nona-, deca-, etc.) to indicate the number of atoms of
that element that are represented in the chemical formula.
The second part of the name will indicate the most electronegative element and will also
contain a prefix (mono-, di-, tri-, tetra-, penta-, hexa-, octa-, nona-, deca-, etc.) to indicate the
number of atoms of that element that are represented in the chemical formula. The second
part of the name will also include the suffix –ide.
Note that if only one atom is represented in the chemical formula for the first part of the name,
the prefix mono- is not applied.
EMPHASIS – Prefixes are usedWhen using systematic (IUPAC) naming rules for binary
compounds, the prefixes relating to the number of atoms represented in the chemical formula
are ONLY….ONLY….ONLY….ONLY… used in Type III binary compounds.
Hydrogen is less electronegative than sulfur so is listed first.
There are two hydrogen atoms, so the prefix di- is used.
Example:
H2S……………………………………………………………………………………..dihydrogen monosulfide
Sulfur is more electronegative than hydrogen so is listed last with –ide suffix.
There is only one sulfur atom, so the prefix mono- is used.
© Bill Ponder
Citations
1. http://www.nhm.ac.uk/about-us/news/2010/august/oldest-tool-use-and-meat-eatingrevealed75831.html; The Near East: Archaeology in the "Cradle of Civilization", Charles
Keith Maisels, Routledge 1993, ISBN 0-415-04742-0
2. http://www.childrenofthecode.org/Tour/c5/power.htm
3. McDougall, Ian; Brown, Francis H.; Fleagle, John G. (17 February 2005). "Stratigraphic
placement and age of modern humans from Kibish, Ethiopia.".Nature 433 (7027): 733–
736; Mayell, Hillary (2003). When Did "Modern" Behavior Emerge in Humans?; Ehrlich,
Paul R. (2002). Human Natures: Genes, Cultures, and the Human Prospect. Island
Press. pp. 159–160.; Diamond, Jared (1999). Guns, Germs, and Steel: The Fate of
Human Societies. W. W. Norton. p. 39.; Mcbrearty (2000). The revolution that wasn’t: a
new interpretation of the origin of modern human behavior
© Bill Ponder