Polyatomic Ions

What they are and how to write their Chemical Formula

Naming Ions, Ionic Compounds, Transition Metals and Writing their

formulas.

Monatomic Ions

• Mono = one• Thus monatomic ions are single atom ions.

Na+ Cl-

Monatomic Ions

Fe3+ O2-

Cations Anions

Ionic Compounds

Cl-Na+

Sodium Chloride

Polyatomic Ions

• poly = many• Thus polyatomic ions are ions composed of

more than one type of atom.• We can represent polyatomic ions as single

units when writing chemical formulas.

OH- CO32-

Hydroxide Carbonate

NH4+

Ammonium

SO3-2

Sulfite

• Calcium has a +2 charge and phosphate has a -3 charge.

Sodium Hydroxide

OH-

Ca2+ PO43-

Na+ NaOH

• Sodium has a +1 charge and hydroxide a -1 charge so they combine in a 1:1 ratio.

Calcium Phosphate

PO43-

• Calcium has a +2 charge and phosphate has a -3 charge.

Sodium Hydroxide

OH-

Ca2+ PO43-

Na+ NaOH

• Sodium has a +1 charge and hydroxide a -1 charge so they combine in a 1:1 ratio.

Calcium Phosphate

Ca2+

Ca2+

Ca3(PO4)2

Ammonium Chloride

Calcium Hydroxide

Ammonium Chloride

Cl-NH4+ NH4Cl

• Ammonium has +1 charge and chloride has a -1 charge so they combine in a 1:1 ratio.

Calcium Hydroxide

Ammonium Chloride

Cl-NH4+ NH4Cl

• Ammonium has +1 charge and chloride has a -1 charge so they combine in a 1:1 ratio.

Calcium Hydroxide

OH-Ca2+

OH-

Ammonium Chloride

Cl-NH4+ NH4Cl

• Ammonium has +1 charge and chloride has a -1 charge so they combine in a 1:1 ratio.

Calcium Hydroxide

OH-Ca2+

• Calcium +2 charge and Hydroxide has a -1 charge so they combine in a 1:2 ratio.

Ca(OH)2

Assignment[1] Analyze the common polyatomic ions, what is the general difference between ate and ite ions...

[2] Write the Chemical formula for the following ionic compounds:

a) Sodium Acetate (hot ice!)b) Potassium Chlorate (gummy bear)c) Iron (III) Bicarbonated) Magnesium Oxalatee) Calcium Nitrate (fertilizer!)

[3] Name these ionic compounds:

a) Li2CrO4

b) K3PO4

c) AgNO3

d) NaHCO3 (baking soda!)