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Nomenclature

Chapter 5

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Common Names - Exceptions

• H2O = water, steam, ice

• NH3 = ammonia

• CH4 = methane

• NaCl = table salt

• C12H22O11 = table sugar

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Naming Starts with Classifying Compounds

• Binary Compounds = only 2 elements

• Compounds containing polyatomic ions

• Acids = formula often starts with H

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Classifying Binary Compounds

• Compounds containing a metal and a nonmetal are binary ionic– Type I and II

• Compounds containing two nonmetals– Type III

• Compounds containing H and a nonmetal = Acids

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Binary Ionic

• Made of metal cation and nonmetal anion

• Name by naming the ions

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Metal Cations

• Type I – Metals that can only have one possible charge– Determine charge by position on the Periodic

Table

• Type II– Metals that can have more than one possible

charge– Determine metal cation’s charge from the

charge on anion

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Type I Binary Ionic Compounds

• Contain Metal Cation + Nonmetal Anion• Metal listed first in formula & name¶ Name metal cation first, name nonmetal

anion second¶ Simple metal cation name is the metal name

– simple metals are Groups 1A, 2A and Al, Ga & In

¶ Nonmetal anion named by changing the ending on the nonmetal name to -ide

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Type II Binary Ionic Compounds• Contain Metal Cation + Nonmetal Anion• Metal listed first in formula & name

¶ Name metal cation first, name nonmetal anion second¶ Metal cation name is the metal name followed by a

Roman Numeral in parentheses to indicate its charge– Determine charge from anion charge– Common Type II cations in Table 5.2

¶ Nonmetal anion named by changing the ending on the nonmetal name to -ide

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Determining the Charge on a Cation – Au2S3

Determine the charge on the anion

Au2S3 - the anion is S, since it is in Group 6A, its charge is -2

Determine the total negative chargesince there are 3 S in the formula, the total negative charge is -6

Determine the total positive chargesince the total negative charge is -6, the total positive charge is +6

Divide by the number of cationssince there are 2 Au in the formula & the total positive charge is +6, each Au has a +3 charge

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Type III - Binary Compounds of 2 Nonmetals

• Name first element in formula first, use the full name of the element

• Name the second element in the formula as if it were an anion– However, remember these compounds do not contain

ions!

• Use a prefix in front of each name to indicate the number of atoms

• Never use the prefix mono- on the first element

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Prefixes

• Drop last “a” in the prefix if the name begins with vowel

octa-8

hepta-7

hexa-6

penta-5

tetra-4

tri-3

di-2

mono-

(not used on first nonmetal)

1

PrefixSubscript

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Compounds Containing Polyatomic Ions

• Polyatomic ions are charged entities that contain more than one atom– Must memorize name, formula and charge– Look for Patterns!!

• Polyatomic compounds contain one or more polyatomic ions

• Name polyatomic compounds by naming cation and anion– Non-polyatomic ions named like Type I and II

• Polyatomic Acids contain H+ and a polyatomic anion

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Patterns for Polyatomic Ions

Elements in the same column on the Periodic Table form similar polyatomic ions– same number of O’s and same charge

ClO3- = chlorate BrO3

- = bromate If the polyatomic ion starts with H, add

hydrogen- before the ions name and add 1 to the chargeCO3

2- = carbonate HCO3- = hydrogen carbonate

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Patterns for Polyatomic Ions

• -ate ion– chlorate = ClO3

-

• -ate ion plus 1 O same charge, per- prefix– perchlorate = ClO4

-

• -ate ion minus 1 O same charge, -ite suffix– chlorite = ClO2

-

• -ate ion minus 2 O same charge, hypo- prefix, -ite suffix– hypochlorite = ClO-

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Acids

• Contain H+ cation and anion

• Binary acids have H+ cation and a nonmetal anion

• Oxyacids have H+ cation and a polyatomic anion

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Writing the Formulas from the Names

• For Type III compounds, use the prefixes to determine the subscripts

• For Type I, Type II, polyatomic Compounds and Acids– Determine the ions present– Determine the charges on the cation and

anion– Balance the charges to get the subscripts