Salts Containing Polyatomic Ions
Acids
Oxyacids
HW: Read 4-4 &4-6 Do problems 32, 34, 47, & 48 on pgs 133-134
 Polyatomic
Ions are groups of more than
one atom that are bonded covalently, and
have a net charge.
 There are several polyatomic ions that
whose names and formulas MUST be
memorized.
 They are found on table 4-2 on page 122.
 This website may also be helpful…
http://antoine.frostburg.edu/chem/senese/101/co
mpounds/polyatomic.shtml

Polyatomic ions are found in nonbinary ionic
compounds, and in oxyacids.

To name a polyatomic Ion in an ionic compound:
• If the poly atomic ion is first, and the anion is monoatomic,
name the polyatomic ion, then name the anion as usual,
replacing its ending with the suffix –ide.
• If the polyatomic ion is second, first name the cation as a type
I or type II depending on what it is, including the roman
numerals for type II, then name the polyatomic ion.
• If both cation and anion are polyatomic, just name each
polyatomic ion in the order in which they occur.
 Na2SO4
 Sodium
sulfate
 Fe(NO3)3
 Iron
 Na2SO3
 Sodium
 KH2PO4
 Potassium
(III) Nitrate
Sulfite
Dihydrogen
Phosphate
 Mn(OH)2
 Manganese
(II) Hydroxide
 NH4ClO3
 Ammonium
Chlorate
 Ca(OH)2
 Calcium
Hydroxide
 Na3PO4
 Sodium
 KMnO4
 Potassium
Phosphate
Permanganate
 (NH4)2Cr2O7  Ammonium
 Co(ClO4)2
 Cobalt
 KClO3
 Potassium
 Cu(NO2)2
 Copper
Dichromate
(II) Perchlorate
Chlorate
(II) Nitrate
 There
are several definitions of acids.
 For
now, an acid is a compound whose
formula starts with hydrogen.
 There
are two types of acids:
1. Regular Acids
2. Oxyacids
 Regular
Acids are binary compounds
containing hydrogen and one other
nonmetal.
 The hydrogen will always come first.
• Examples: HCl, H2S, H3N
 How
do you tell how many H’s the acid of
a nonmetal will have?
• Balance the known charge of the nonmetal by
adding Hydrogen (each H = 1+ charge).
 Naming Regular Acids
1. Use the prefix Hydro2. Use the nonmetal’s root
3. Use the suffix –ic
4. Finish with the word acid.
 Hydro-”root”-ic Acid
• HCl = Hydrochloric Acid
• H2S = Hydrosulfuric Acid
• H3N = Hydronitric Acid
 HF
 Hydrofluoric
Acid
 HI
 Hydroiodic
 HBr
 Hydrobromic
 H2O
 Hydroxic
 H2Se
 Hydroselenic
Acid
 H3As
 Hydroarsenic
Acid
 H3P
 Hydrophosphoric
Acid
Acid
Acid
Acid
 Oxyacids
contain hydrogen, oxygen, plus
one other nonmetal..
 The hydrogen comes first.
 The oxygen and other element make up a
polyatomic anion called an oxyanion.
• Example: ClO4-, CO32-, NO3-, NO2-, etc…
 Remember
you add the number of
hydrogen atoms needed to balance the
charge on the oxyanion.
 Oxyacids
are named using the oxyanions from
which they are made.
 If the oxyanion ends in –ate, then the suffix is
changed to –ic, followed by the word acid.
• HNO3 contains nitrate (NO3-): it is called nitric acid
 If
the oxyanion ends in –ite, then the suffix is
changed to –ous, followed by the word acid.
• HNO2 contains nitrite (NO2-): it is called nitrous acid
 H2SO4
 Sulfuric
Acid
 H2SO3
 Sulfurous
 H3PO4
 Phorphoric
 H2CO3
 Carbonic
 HClO
 Hypochlorous
 HC2H3O2
 Acetic
 HCN
 Hydrocyanic
Acid
Acid
Acid
Acid
Acid
Acid