Transcript 3-Nomenclature-2007

Nomenclature
(Compounds: Formulas & Names)
Dr. Ron Rusay
Spring 2008
© Copyright 2008 R.J. Rusay
Chemical Formulas
and Naming
• Molecular Formula:
•
Elements’ Symbols = atoms
•
Subscripts = relative numbers of atoms
• How are compounds named?
CaCl2
CCl4
NaOH
(NH4)2CO3
C20H26N2O (Ibogaine)
Nomenclature
• Nomenclature: the naming of compounds
• Governed by the IUPAC: International
Union of Pure and Applied Chemistry
• International rules are updated periodically
• General schemes and examples follow:
Naming Compounds
Binary Ionic Compounds:
For example; CaCl2
• Name cation first, then anion
• Monatomic cation = name of the element
• Ca2+ = calcium ion
• Anion = root + -ide
ide
• Cl = chlorine
CaCl2 = calcium chloride
Common Monatomic Cations
and Anions
Common Cations and Anions
Naming Compounds
(continued)
Binary Ionic Compounds (Type II):
• metal forms more than one cation: Pb2+ or possibly Pb4+
? Ambiguous?
• option 1) use Roman numeral in name
• If Pb2+ is the cation; eg. PbCl2 :
• PbCl2 = lead (II) chloride
• or 2) use name (latinized) + suffix: -ous (lower) or -ic (higher)
Plumbum
Plumbous
Common
Type II
Cations
Naming Compounds
(continued)
Binary compounds (Type III):
•
•
Compounds formed between two nonmetals
First element in the formula is named first. It is
the more electropositive.
•
Second element is named as if it were an
anion.
•
Use prefixes to count the # of atoms.
•
Do not normally use mono as a prefix.-
• P2O5 = diphosphorus pentoxide
Prefixes & The Number of Atoms
Compounds with more than
two different elements
• Polyatomic ions: [oxygen as the third atom]
http://chemconnections.llnl.gov/general/Chem120/polyatomics.html
QUESTION
The correct name for LiCl is:
1) lithium monochloride.
2) lithium (I) chloride.
3) monolithium chloride.
4) lithium chloride.
5) monolithium monochloride.
ANSWER
4)
lithium chloride.
Section 2.8 Naming Simple Compounds (p. 57)
Lithium is a Group IA metal, so it always forms a
+1 ion. Therefore, no roman numeral is
necessary.
QUESTION
The correct name for FeO is:
1) iron oxide.
2) iron (II) oxide.
3) iron (III) oxide.
4) iron monoxide.
5) iron (I) oxide.
ANSWER
2)
iron (II) oxide.
Section 2.8 Naming Simple Compounds (p. 57)
Iron is a transition metal that forms more than
one type of ion. A roman numeral is needed to
indicate which ion is present in the compound.
QUESTION
Of the following, which provides the most acceptable name
for Fe2(C2O4)3?
1.
2.
3.
4.
Iron (II) oxalate
Iron (II) oxalate (III)
Iron (III) trioxalate
Iron (III) oxalate
ANSWER
Choice 4 is correct. Since iron can form compounds where it
is commonly a +2 or +3, the roman numeral must be provided
to indicate the charge (+3 in this case.) Since the iron charge
is specified it is not necessary to indicate the number of
oxalate ions present.
Section 2.8: Naming Simple Compounds
QUESTION
Which of the following provides the correct name for
Ca(H2PO4)2?
1.
2.
3.
4.
Calcium dihydrogen phosphate
Calcium (II) hydrogen phosphate
Calcium di-dihydrogen phosphate
Calcium (II) dihydrogen phosphate
ANSWER
Choice 1 provides the correct name for Ca(H2PO4)2. It is not
necessary to use roman numerals when an atom typically only
has one oxidation state (such as calcium’s +2.) Also, the anion
combination only has one possibility here so it does not need a
prefix Ca(H2PO4)2.
Section 2.8: Naming Simple Compounds
Naming Acids
[Compounds with electropositive Hydrogen
atom(s)]
QUESTION
Hypochlorous acid is related to the anion found in common
household bleach. Which of the following is that common
anion?
1.
2.
3.
4.
ClO4–
ClO3–
ClO2–
ClO–
ANSWER
Choice 4 represents the hypochlorite ion, ClO–, that can be
made to form hypochlorous acid HClO.
Section 2.8: Naming Simple Compounds
Names from Formulas
Name the following
• SO2
CaBr2
Zn(NO3)2
• PCl5
( NH4)2SO4
FeO
• HI(aq)
HBrO
NaClO4
Names from Formulas
• Solutions:
• Sulfur dioxide Calcium bromide
Zinc nitrate
• Phosphorus pentachloride
Ammonium sulfate
Iron(II) oxide
• Hydroiodic acid
Hypobromous acid
Sodium perchlorate
Formulas from Names
Provide formulas for the following
•
•
•
•
•
•
•
•
•
Sulfur trioxide
Magnesium chloride
Lead (IV) sulfate
Diphosphorus pentasulfide
Ammonium phosphate
Iron (III) oxide
Hydrobromic acid
Chloric acid
Sodium chlorite
Formulas from Names
• Solutions:
• SO3
MgCl2
Pb(SO4 )2
• P2S5
( NH 4 )3PO4
Fe2 O3
• HBr
HClO3
NaClO2