Chapter 5Nomenclature

Binary compounds: only 2 elements

Compounds containing polyatomic ions

Acids: formulas often start with H

Naming Starts with Classifying Compounds

Binary ionic compounds contain a metal and a nonmetal.◦ Type I and II

Compounds containing two nonmetals◦ Type III

Compounds containing H and a nonmetal = Acids

Classifying Binary Compounds

Made of metal cation and nonmetal anion

Name by naming the ions

Binary Ionic

Type I ◦ Metals that can only have one possible

charge◦ Charge determined by position on the

Periodic Table Type II

◦ Metals that can have more than one possible charge

◦ Metal cation’s charge determined from the charge on anion

Metal Cations

Contain Metal Cation from Groups 1A, 2A or Al, Ga, & In (metals with only one possible ionic charge) + Nonmetal Anion

Metal listed first in formula & name Name metal cation first, name nonmetal

anion second Nonmetal anion named by changing the

ending on the nonmetal name to –ide Lets do some examples Self-Check 5.1 Page 117

Type I Binary Ionic Compounds

Contain metal cation of possible variable ionic charge + nonmetal anion

Metal listed first in formula & name

Name metal cation first and nonmetal anion second

Type II Binary Ionic Compounds

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

Type II Binary Ionic Compounds (cont.)

Determine the charge on the anion◦ Au2S3: the anion is S, since it is in Group 6A,

and its charge is –2 Determine the total negative charge

◦ Since there are 3 S in the formula, the total negative charge is –6

Determine the total positive charge◦ Since the total negative charge is -6, the total

positive charge is +6 Divide by the number of cations

◦ Since there are 2 Au in the formula & the total positive charge is +6, each Au has a +3 charge

◦ Self-Check 5.2 Page 121

Determining the Charge on a Cation – Au2S3

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.

Type III - Binary Compounds of 2 Nonmetals

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

Prefixes

octa-8hepta-7hexa-6penta-5tetra-4tri-3di-2

mono- (not used on first nonmetal)

1PrefixSubscript

Roadmap for Naming Binary Compounds

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.

Compounds Containing 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.

Compounds Containing Polyatomic Ions (cont.)

Names of Common Polyatomic Ions

Elements in the same column on the periodic table form similar polyatomic ions.

◦ Same number of O’s and same chargeClO3

- = chlorate BrO3- = bromate

If the polyatomic ion starts with H, add hydrogen- before the ions name and add 1 to the charge.

CO32- = carbonate HCO3

- = hydrogen carbonate

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-

Patterns for Polyatomic Ions (cont.)

Formulas always begin with H as first element

Can be thought of as consisting of H+ cation and anion

Binary acids have H+ cation and a nonmetal anion

Oxyacids have H+ cation and a polyatomic anion

Acids

Naming Acids

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

Writing the Formulas from the Names