Polyatomic Ions

Question 1

Polyatomic ions

Answer 1

• Ions that are themselves composed of two or more atoms linked by the same covalent bonds that hold molecules together… but they have a charge.
• Trick to identify the charge: If the total of the group numbers of the atoms is odd, it will have a charge of 1-. (Except for phosphate, -3.) If the total is even, it will have a charge of 2-.
• -ate has one more Oxygen than -ite.

Question 2

NH₄ +

Answer 2

ammonium

(Note that the only positive common polyatomic ions are this, and hydronium H₃O+.

Note that ammonium is different from the compound ammonia, NH₃.)

Question 3

H3O +

Answer 3

hydronium (always in aqueous solutions)

Question 4

CN -

Answer 4

cyanide

Question 5

OH -

Answer 5

hydroxide

Question 6

NO₂ -

Answer 6

nitrite

Question 7

NO₃ -

Answer 7

Nitrate

(Hint: Nina, 3 girls. Nitrite is NO₂-.)

Question 8

ClO -

or OCl -

Answer 8

Hypochlorite

(Order: hypochlorite, chlorite, chlorate, perchlorate)

Question 9

ClO₂ -

Answer 9

Chlorite

(Order: hypochlorite, chlorite, chlorate, perchlorate)

Question 10

ClO₃ -

Answer 10

Chlorate

(Order: hypochlorite, chlorite, chlorate, perchlorate)

Question 11

ClO_{<span>4</span>} -

Answer 11

perchlorate

(Order: hypochlorite, chlorite, chlorate, perchlorate)

Question 12

MnO₄ -

Answer 12

permanganate

Question 13

C₂H₃O₂ -

Answer 13

acetate

Question 14

C₂O₄ ^2-

Answer 14

oxalate

Question 15

CO₃ ^2-

Answer 15

carbonate

Question 16

HCO₃ -

Answer 16

hydrogen carbonate

aka bicarbonate ion

Question 17

SO₃ ^2-

Answer 17

sulfite

Question 18

HSO₃ -

Answer 18

hydrogen sulfite

aka bisulfite

Question 19

SO₄ ^2-

Answer 19

sulfate

Question 20

HSO₄ -

Answer 20

hydrogen sulfate

aka bisulfate

Question 21

SCN ^-

Answer 21

thiocyanate

Question 22

S₂O₃ ^2-

Answer 22

thiosulfate

(Hint: Two weird sulfur. Thiree-O’s.)

Question 23

CrO₄ ^2-

Answer 23

chromate

(dichromate is Cr₂O₇^2-)

Question 24

Cr₂O₇ ^2-

Answer 24

dichromate

(just chromate is CrO_{4<span> </span>}^2-)

Question 25

PO₄ ^3-

Answer 25

phosphate

Question 26

HPO₄ ^2-

Answer 26

monohydrogen phosphate (meanwhile dihydrogen phosphate just has another H: H₂PO₄-)

Question 27

H₂PO₄^-

Answer 27

dihydrogen phosphate (one more hydrogen than hydrogen phosphate HPO₄ ^2-)

Question 28

# What is the formula for this polyatomic ion? ammonium

Answer 28

NH₄ +

Question 29

# What is the formula for this polyatomic ion? hydronium (always in aqueous solutions)

Answer 29

H3O +

Question 30

# What is the formula for this polyatomic ion? cyanide

Answer 30

CN -

Question 31

# What is the formula for this polyatomic ion? ## Footnote hydroxide

Answer 31

OH -

Question 32

# What is the formula for this polyatomic ion? nitrite

Answer 32

NO₂ -

Question 33

# What is the formula for this polyatomic ion? Nitrate

Answer 33

NO₃ -

Question 34

# What is the formula for this polyatomic ion? Hypochlorite (Order: hypochlorite, chlorite, chlorate, perchlorate)

Answer 34

ClO - or OCl -

Question 35

# What is the formula for this polyatomic ion? Chlorite (Order: hypochlorite, chlorite, chlorate, perchlorate)

Answer 35

ClO₂ -

Question 36

# What is the formula for this polyatomic ion? Chlorate (Order: hypochlorite, chlorite, chlorate, perchlorate)

Answer 36

ClO₃

Question 37

# What is the formula for this polyatomic ion? perchlorate (Order: hypochlorite, chlorite, chlorate, perchlorate)

Answer 37

ClO₄ -

Question 38

# What is the formula for this polyatomic ion? permanganate

Answer 38

MnO₄ -

Question 39

# What is the formula for this polyatomic ion? acetate

Answer 39

C₂H₃O₂ - Pam writes this as CH₃COO (Either works.)

Question 40

# What is the formula for this polyatomic ion? oxalate

Answer 40

C₂O₄ ^2-

Question 41

# What is the formula for this polyatomic ion? carbonate

Answer 41

CO₃ ^2-

Question 42

# What is the formula for this polyatomic ion? hydrogen carbonate aka bicarbonate ion

Answer 42

HCO₃ -

Question 43

# What is the formula for this polyatomic ion? sulfite

Answer 43

SO₃ ^2-

Question 44

# What is the formula for this polyatomic ion? hydrogen sulfite aka bisulfite

Answer 44

HSO₃ -

Question 45

# What is the formula for this polyatomic ion? sulfate

Answer 45

SO₄ ^2-

Question 46

# What is the formula for this polyatomic ion? hydrogen sulfate aka bisulfate

Answer 46

HSO₄ -

Question 47

# What is the formula for this polyatomic ion? thiocyanate

Answer 47

SCN ^-

Question 48

# What is the formula for this polyatomic ion? thiosulfate

Answer 48

S₂O₃ ^2- (Hint: Two weird, thio-three O.)

Question 49

# What is the formula for this polyatomic ion? chromate

Answer 49

CrO₄ ^2-

Question 50

# What is the formula for this polyatomic ion? dichromate

Answer 50

Cr₂O₇ ^2-

Question 51

# What is the formula for this polyatomic ion? phosphate

Answer 51

PO₄ ^3-

Question 52

# What is the formula for this polyatomic ion? monohydrogen phosphate

Answer 52

HPO₄ ^2-

Question 53

# What is the formula for this polyatomic ion? dihydrogen phosphate

Answer 53

H₂PO₄^-