NOMENCLATURE
CHEM& 151
Fall 2009
Fill-in-You must get a stamp from a laboratory instructor during lab time, before the due date.
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Lecture Instructor
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LEARNING OBJECTIVES After completing this experiment, you should feel comfortable with:
•
Recognizing when a compound is an ionic compound and when it is a binary compound.
•
Using IUPAC methods to name inorganic and binary compounds.
•
Writing balanced formula based on the names of compounds.
•
Naming compounds with hydrogen cations as ionic compounds or as acids as appropriate.
TO EARN YOUR FINAL STAMP: The following items must be completed in the lab. You may
complete the entire assignment in lab, this reflect the minimum required to earn your final stamp.
 Complete the entire worksheet. You may work on the worksheet outside of the lab, however
you MUST have it completed all tables and all of the ‘Hodgepodge’ items to get a stamp.
The lab instructor will check over your lab worksheet when you get it stamped.
INTRODUCTION
Chemical reagent bottles in laboratories are sometimes labeled by name, sometimes by symbol. In
order to be sure you are using the proper reagent, an understanding of chemical nomenclature is
necessary. In this experiment you will learn the rules for naming inorganic compounds and you will
then apply these rules to a number of examples.
Discussion
Not only are compounds represented in chemistry by their chemical names, almost every
household product has its ingredients listed on its container. In some cases, a common or trade name
is used instead of the chemical name, but in most cases it is listed by its proper chemical title.
Because there are several ways compounds could be named, chemists early on realized that a
standardized procedure of nomenclature was needed so that every compound can be named from its
formula and that only one formula can be assigned to a given name.
The IUPAC (the International Union of Pure and Applied Chemistry) rules divide inorganic
compounds into two classes: binary compounds which consist of two elements, and ternary
compounds which consist of three or more elements.
For most classes of compounds, the more positive portion of the compound consisting of a metal,
a positive polyatomic ion, H+, or the less electronegative nonmetal is represented first. The negative
portion of the compound, the more electronegative nonmetal or negative polyatomic ion, follows
this. Naming starts with the positive portion.
As a general rule for ionic compounds, write the name of the positive ion followed by the name
of the negative ion. Be sure to know the ions on your list.
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Examples:
Binary compounds, where only two elements are present, fall into 2 classes:
Ionic: metal + nonmetal
example: metal (Na, sodium) + nonmetal (Cl, chlorine  chloride)  NaCl sodium chloride
Note that for ionic compounds, the sum of all charges is zero. Enough of each positive and
negative ion is combined to form a neutral compound.
Covalent(molecular): nonmetal + nonmetal
example: nonmetal (N, nitrogen) + nonmetal (O, oxygen  oxide)  NO2 nitrogen dioxide
example: nonmetal (N, nitrogen) + nonmetal (O, oxygen  oxide)  N2O4 dinitrogen tetraoxide
Note that for covalent compounds there are no ions!
Ternary compounds, where three or more elements are present, are generally ionic. They consist of
a metal (positive species) and a negative polyatomic ion or a positive polyatomic ion and a negative
polyatomic ion or even a positive polyatomic ion and a nonmetal.
example: sodium (Na+1) + phosphate ion (PO43-)  Na3PO4 sodium phosphate
example: ammonium ion (NH4+) + nitrate ion (NO3-)  NH4NO3 ammonium nitrate
example: ammonium ion (NH4+) + chloride ion (Cl-)  NH4Cl ammonium chloride
You will need to memorize a certain number of atomic charges/oxidation states and
polyatomic ions as indicated by your instructor. Refer to your textbook for a discussion on
oxidation numbers.
Naming Compounds
1. Metal Containing Binary Compounds (2 elements, generally ionic)
When a metal and a non-metal combine to form an ionic compound, the name for the compound
consists of the name of the positive portion (metal) followed by the name of the negative portion.
A. Positive portion (cation): metals, or elements with a positive atomic charge or oxidation
number (metals will always be positive). See Table 1 for a list.
Type I: If the metal or element with the positive oxidation number has only one oxidation
number possible, use the regular name of the element.
Group IA (1A) metal ions all have a charge of +1
Group IIA (2A) metal ions all have a charge of +2
Group IIIA (3A) metal ions all have a charge of +3
Examples:
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Na — always +1, named sodium
Ba — always +2, named barium
Ga — always +3, named gallium
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Type II: If the element with the positive oxidation number or the metal has two (divalent) or
more (multivalent) oxidation states there are two methods for naming the positive
part (cation).
1. IUPAC Method - Use the element's regular name with the oxidation state
written as a Roman numeral in parentheses following the name. (this is used
with most transition elements and some heavier main group elements, such as
mercury and lead)
Example:
copper (I) for Cu+1 and copper (II) for Cu+2
b. Common Name Method - Change the last syllable of the Latin name to -ous
for the lower oxidation number or to -ic for the higher oxidation number.
Example:
cuprous for Cu+1 and cupric for Cu+2
B. Negative portion: nonmetals with a negative oxidation number/atomic charge. See Table
2 for a list.
Typically Groups V, VI and VIIA (5A, 6A, and 7A): N3-, O2-, Cl-.
The root name, typically the first syllable of the element name, with –ide.
Example: oxygen becomes oxide and bromine becomes bromide
2. Non-metal Binary Compounds (two nonmetals combined, molecular and covalent)
When two nonmetals form a binary compound, another method is used for naming. For
these compounds, the number of atoms of each element is indicated using the Greek prefixes
shown below. The first element (less electronegative) has the same name as the element's
name. If only one atom of the first element is present, the name is the same as the element.
If more than one of the first element is present, a numerical prefix is used before the
element’s name. The second nonmetal ALWAYS gets a numerical prefix in the name. This
second (more electronegative) element keeps the root portion of its name and ends in ide.
Greek prefix:
Number
mono- di1
2
Example:
tri3
tetra- penta- hexa- hepta- octa4
5
6
7
8
nona- deca6
10
CO — carbon monoxide
PCl3 — phosphorous trichloride
N2O4 — dinitrogen tetroxide
3. Ternary Compounds (three or more elements, usually ionic)
The name for ternary compounds is comprised of the name of the positive ion (cation) and the
name of the negative ion (anion). The prefixes are not used to indicate multiple ions.
A. For the positive portion use the same rules for metal ions as were used for the binary
compounds (see 1A). For polyatomic cations, use their name (ex: NH4+ ammonium).
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B. Many polyatomic anions involve a central atom surrounded by some number of oxygen
atoms. These are called oxoanions. Use the one of the following rules to name these
anions.
1) For those with the lower oxidation number (or a smaller number of oxygens) on
the central atom, use the stem name of the central atom plus ite for the ending
syllable.
2) For those with the higher oxidation number on the central atom, use the stem
name plus ate for the ending syllable.
Example: oxidation state
S = +4
S = +6
polyatomic anion
name
SO3
-2
sulfite
SO4
-2
sulfate
3) If a central atom exists in two or more polyatomic anions at the same oxidation
state in combination with oxygen, use appropriate prefixes such as meta and
ortho, or di, tri, tetra in front of the polyatomic ion names. You are expected to
memorize only those indicated in class.
Example:
oxidation state
polyatomic anion
name
Cr = +6
CrO4-2
chromate
Cr = +6
Cr2O7
-2
dichromate
4) If a central atom exists in several polyatomic anions at different oxidation states
when combined with oxygen, use appropriate prefixes such as hypo and per in
front of the polyatomic ion name. You are expected to memorize only those
indicated in class.
Example:
oxidation state
polyatomic anion
name
lowest oxidation #
Cl = +1
ClO-1
hypochlorite
lower oxidation #
Cl = +3
ClO2-1
chlorite
higher oxidation #
Cl = +5
ClO3-1
chlorate
highest oxidation #
Cl = +7
ClO4-1
perchlorate
More examples:
Ca+2 calcium ClO-1 hypochlorite
Zn+2 zinc (monovalent) CO3-2 carbonate
Fe+3 iron (III) CrO4-2 chromate
K+ potassium PO43- phosphate
Na+ sodium H2PO4- dihydrogenphosphate
Ca(ClO)2 calcium hypochlorite
ZnCO3 zinc carbonate
Fe2(CrO4)3 iron (III) chromate
K3PO4 potassium phosphate
NaH2PO4 sodium dihydrogenphosphate
4.
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Compounds Containing Acidic Hydrogen(s). Acidic compounds are named as acids ONLY when
they are aqueous solutions, i.e. dissolved in water. They have (aq) after the formula.
A. If the compound is binary (hydrogen and a non-metal), the ide portion from the anion
name changes to ic and a hydro precedes the root name for that non-metal element. In
all acids, the word acid is part of the name – notice the aq after the formula.
Examples formula
name
HX (g)
Hydrogen rootide
HX (aq)
Hydrorootic acid
HBr (g)
hydrogen bromide
HBr (aq)
hydrobromic acid
H2S (g)
hydrogen sulfide
H2S (aq)
hydrosulfuric acid
B. If the compound is ternary (hydrogen and a polyatomic ion): and the name ends in ite for
the anion: if the species is a gas, it is named hydrogen polyatomic ion. If the species is
aqueous, the ite from the polyatomic ion changes to ous, the hydro is dropped from the
name and the word acid is added as a suffix.
Examples formula
name
H2SO3 (g)
hydrogen sulfite
H2SO3 (aq)
sulfurous acid
C. If the compound is ternary (hydrogen and a polyatomic ion): and the name ends in ate for
the anion: if the species is a gas, it is named hydrogen polyatomic ion. If the species is
aqueous, the ate from the polyatomic ion changes to ic, the hydro is dropped from the
name and the word acid is added as a suffix.
Examples formula
name
H2SO4 (g)
hydrogen sulfate
H2SO4 (aq)
sulfuric acid
More examples:
HClO4 (aq)
anion is perchlorate
perchloric acid
HClO3 (aq)
anion is chlorate
chloric acid
HClO2 (aq)
anion is chlorite
chlorous acid
HClO (aq)
anion is hypochlorite
hypochlorous acid
HCl (aq)
anion is chloride
hydrochloric acid
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TABLE 1
COMMON CATIONS AND THEIR OXIDATION NUMBERS
1+
Group IA (1A)
2+
Group IIA (2A)
NH4+ ammonium
Cd2+ cadmium
Cu+ copper (I) or
cuprous
Cu2+ copper (II) or
cupric
3+
Group IIIA (3A)
4+
Cr3+ chromium (III) or
chromic
Hg22+ mercury (I) or
mercurous (+Hg–Hg+)
Co2+ cobalt (II) or
cobaltous
Co3+ cobalt (III) or
cobaltic
Fe2+ iron (II) or
ferrous
Fe3+ iron (III) or ferric
Hg2+ mercury (II) or
mercuric
Ni2+ nickel (II) or
nickelous
Ni3+ nickel (III) or
nickelate
Pb2+ lead (II) or
plumbous
Pb4+ lead (IV) or
plumbic
Pd2+ palladium (II) or
palladous
Pd4+ palladium (IV) or
palladic
Pt2+ platinum (II)
Pt4+ platinum (IV)
Sn2+ tin (II) or
stannous
Sn4+ tin (IV) of
stannic
Ag+ silver
Zn2+ zinc
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TABLE 2
COMMON ANIONS, POLYATOMIC IONS AND THEIR OXIDATION NUMBERS
1-
2-
3-
Group VIIA (7A)
Group VIA (6A)
Group VA (5A)
Br- bromide
O2- oxide
Cl- chloride
S2- sulfide
H- hydride
Se2- selenide
N3- nitride
F- fluoride
Te2- telluride
P3- phosphide
I- Iodide
C2H3O2- acetate
PO33- phosphite
H2PO4- dihydrogen phosphate
HPO42- hydrogen phosphate
HCO3- bicarbonate or
hydrogen carbonate
CO32- carbonate
PO43- phosphate
CrO42- chromate
Cr2O72- dichromate
HSO3- bisulfite or hydrogen
sulfite
HSO4- bisulfate or hydrogen
sulfate
SO32- sulfite
SO42- sulfate
S2O32- thiosulfate
ClO- hypochlorite
C2O42- oxalate
ClO2- chlorite
ClO3- chlorate
O22- peroxide
ClO4- perchlorate
OH- hydroxide
MnO4- permanganate
NO2- nitrite
NO3- nitrate
SCN- thiocyanate
CN- cyanide
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DRILLS:
Formulas and Equations: Each blank in the table below is to be filled in with the
formula of the neutral compound resulting when the cation at the left is combined with the anion at
the top.
Br-1
SO4-2
NO3-1
S-2
PO4-3
H+1
K+1
Zn+2
Cu+2
Fe+3
Al+3
Sn+4
DRILLS: Formulas and Equations: Each blank in the table below is to be filled in with the
NAME of the neutral compound resulting when the cation at the left is combined with
the anion at the top. Hydrogen containing compounds are to be named as acids.
Br-1
SO4-2
NO3-1
S-2
PO4-3
H+1
K+1
Zn+2
Cu+2
Fe+3
Al+3
Sn+4
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Formula Writing and Compound Naming – Ionic Compounds
A.
Name or write formulas for the following ionic compounds: note – re-read the section on
IONIC name and formula writing!
1. Ca3(PO4)2 _________________________________________________________
2. AlBr3 _____________________________________________________________
3. Iron (III) chloride ___________________________________________________
4. Ammonium dichromate ______________________________________________
5. Mg(OH)2 _________________________________________________________
6. H2SO4 (aq) ________________________________________________________
7. Pt(NO3)2 __________________________________________________________
8. Barium bisulfate ____________________________________________________
9. CuF ______________________________________________________________
B.
Name or write formulas for the following molecular/covalent compounds: note – re-read the
section on covalent name and formula writing!
1. SO3 ______________________________________________________________
2. Carbon dioxide ____________________________________________________
3. O2 ______________________________________________________________
4. N2O ____________________________________________________________
5. Phosphorus trichloride ______________________________________________
6. N2O5 ____________________________________________________________
7. CCl4 ____________________________________________________________
8. Xenon hexafluoride ________________________________________________
9. Iodine monobromide _______________________________________________
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C.
Hodgepodge: Write symbols and formulas for the following elements and ionic/covalent
compounds:
1. Sodium bicarbonate ______________________________________________________
2. Oxygen molecule _______________________________________________________
3. Gold (I) nitrate _________________________________________________________
4. Calcium hypochlorite ____________________________________________________
5. Cl2 (g) _________________________________________________________________
6. Cupric dihydrogen phosphate ______________________________________________
7. Lithium nitride _________________________________________________________
8. Pb ___________________________________________________________________
9. Zinc permanganate ______________________________________________________
10. Ag2C2O4 ______________________________________________________________
11. NH4Cl ________________________________________________________________
12. CO ___________________________________________________________________
13. Iron (III) oxide __________________________________________________________
14. Perchloric acid __________________________________________________________
15. Na3PO4 ________________________________________________________________
16. Potassium acetate ________________________________________________________
17. Copper (II) bromide ______________________________________________________
18. Arsenic pentachloride _____________________________________________________
19. Nitrous acid _____________________________________________________________
20. Hydrogen chlorate ________________________________________________________
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