Polyatomic Ions—This IS Important!

All General Chemistry students must memorize the name and formula for each of the thirty Poly-atomic Ions (PAIs) on this list. Your first PAI Quiz will be on Friday, October 5th. It will cover PAIs 1 through 5. One week later you will have PAI Quiz #2 on ions 1 through 10. Five more ions will be added each week, in order, from the list below, until 1 through 30 are included in the PAI Quizzes. Quizzes covering all 30 ions will not cease until the class average on these quizzes reaches 75%. Refresher quizzes may be given at any time during Chemistry A or Chemistry B.

LEARN THEM AND DO NOT FORGET THEM.

Formula / Name / Notes
1 / H2PO41- / Dihydrogen Phosphate
2 / C2H3O21- / Acetate
3 / HSO31- / Hydrogen Sulfite
4 / HSO41- / Hydrogen Sulfate
5 / HCO31- / Hydrogen Carbonate
6 / NO21- / Nitrite
7 / NO31- / Nitrate
8 / CN1- / Cyanide
9 / OH1- / Hydroxide
10 / MnO41- / Permanganate
11 / ClO1- / Hypochlorite
12 / ClO21- / Chlorite
13 / ClO31- / Chlorate
14 / ClO41- / Perchlorate
15 / H1- / Hydride
16 / HPO42- / Hydrogen Phosphate
17 / C2O42- / Oxalate
18 / SO32- / Sulfite
19 / SO42- / Sulfate
20 / CO32- / Carbonate
21 / CrO42- / Chromate
22 / Cr2O72- / Dichromate
23 / SiO32- / Silicate
24 / O22- / Peroxide
25 / PO43- / Phosphate
26 / PO33- / Phosphite
27 / SCN1- / Thiocyanate
28 / H3O+ / Hydronium (Cation)
29 / NH4+ / Ammonium Ion (Cation)
30 / Hg22+ / Mercury (I) Ion (Cation)

Polyatomic Ions

On the front of the index card write the name of the polyatomic ion and on the back of the index card write the formula with the charge. We will be testing ions every week during the first semester. Each week you will memorize five ions or more and need to be able to recall the previous ions from the last week and during the sixth week there will be a quiz over the entire list of ions. Memorization of these ions is crucial to your success in this class.

30 Polyatomic Ions

(1-) charge / (2-) charge / (3-) charge
Formula / Name / Formula / Name / Formula / Name
H2PO41-
C2H3O21-
HSO31-
HSO41-
HCO31-
NO21-
NO31-
CN1-
OH1-
MnO41-
ClO-
ClO21-
ClO31-
ClO41-
H1-
SCN1- / Dihydrogen Phosphate
Acetate
Hydrogen Sulfite
Hydrogen Sulfate
Hydrogen Carbonate
Nitrite
Nitrate
Cyanide
Hydroxide
Permanganate
Hypochlorite
Chlorite
Chlorate
Perchlorate
Hydride
Thiocyanate / HPO42-
C2O42-
SO32-
SO42-
CO32-
CrO42-
Cr2O72-
SiO32-
O22-
HPO32- / Hydrogen Phosphate
Oxalate
Sulfite
Sulfate
Carbonate
Chromate
Dichromate
Silicate
Peroxide
Hydrogen
Phosphite / PO43-
PO33- / Phosphate
Phosphite
Cations
positive charge
NH1+ / Ammonium
H3O1+ / Hydronium
Hg22+ / Mercury (I)

Some other anions you may encounter

IO31-
BrO31-
HCOO1-
OCN1- / Iodate
Bromate
Formate
Cyanate / S2O32-
S2O22-
C4H4O62- / Thiosulfate
Thiosulfite
Tartrate / C6H5O73-
AsO43-
AsO33- / Citrate
Arsenate
Arsenite