Writing Ionic Polyatomic Formulas

Chemical Nomenclature

PART 2: Naming Writing Formulas for Ionic

Compounds containing Polyatomic Ions

Naming and Writing

Formulas with
Polyatomic Ions

By the end of class I will be able to...

• Name ionic compounds containing Polyatomic Ions using
the IUPAC nomenclature rules

• Write the formula of ionic compounds containing
Polyatomic Ions when given the IUPAC name.

Ex: Al2(SO)3 is Aluminum Sulfate

Terms to Know
- Polyatomic Ion ( Poly = MANY)

Composed of a group of
atoms with one net charge

- Most common Polyatomic Ions

Naming Binary Formulas

1. Write the name of the cation

- If it’s a polyatomic ion, write the name

2. Write the name of the anion.

- If it’s an anion, drop the ending and add -ide
- If it’s a polyatomic ion, write the name.

CRISS-CROSS Method

1. Write the formulas for the cation and polyatomic

ion, including the oxidation number!

2. The oxidation number of the cations and polyatomic

ions will be switched. ( Ignore the + and - signs)

3. Reduce the oxidation numbers if needed.

1

2
Ca2+OH-

Ca(OH)2

Let’s Practice!!!

Multiple Choice

What is the correct charge of Chromium in the formula shown:

CrCl₃

• +1

• +2

• +3

Multiple Choice

What is the correct name for the formula shown:

VF₅

• Vanadium fluoride

• Vanadium (V) fluorine

• Vanadium (V) fluoride

• Vanadium fluorine

Multiple Choice

What is the correct name for the polyatomic ion below?

CO₃^2-

• carbon

• carbide

• carbonate

• carbonite

Multiple Choice

What is the correct formula for sulfate ion?

• SO₃^2-

• SO₄^2-

• SO₂^4-

• SO₂^3-

Multiple Choice

What is the correct formula for the compound named "aluminum nitrate"

• AlNO₃

• Al₃NO₃

• Al(NO₃)₃

• Al₃(NO₃)₃

Multiple Choice

What is the correct formula for the compound named "calcium phosphate"

• CaPO₄

• Ca₂(PO₄)₃

• Ca₃(PO₄)₂

Multiple Choice

What is the correct formula for the compound: "ammonium sulfite"

• NH₄SO₃

• (NH₄)₂SO₃

• (NH₄)₂SO₄

• NH₄(SO₃)₂

Multiple Choice

What is the correct name for the following formula:

CuNO₃

• copper nitrate

• copper (I) nitrate

• copper (II) nitrate

• none of these

Multiple Choice

What is the correct formula for the polyatomic ion called chlorate?

• ClO^–

• ClO₂^–

• ClO₃^–

• ClO₄^–

Multiple Choice

Which of the following is the correct name for the chemical formula Ca(NO₂)₂?

• cadmium nitride
• calcium nitrate
• calcium nitrite
• cadmium nitrite

Multiple Choice

The name of Al₂(SO₄)₃ is

• aluminum sulfur oxide
• aluminum sulfate
• aluminum trisulfate
• aluminum (III) sulfate

Multiple Choice

What is the name of NH₄Cl?

• nitrogen tetrahydrogen chloride
• ammonium chlorine
• ammonium chloride
• ammonium chlorate

Multiple Choice

What is the formula for sodium nitrate?

• Na₃NO
• NaNO
• Na₃NO₃
• NaNO₃

Multiple Choice

What is the formula for iron(II) carbonate?

• Fe₂CO₃
• FeCO₃
• Fe₂CO2
• FeCO4

Multiple Choice

What is the name of K₃PO₄?

• Tripotassium Phosphate
• Tripotassium Phosphite
• Potassium phosphide
• Potassium phosphate

Multiple Choice

Name the following ionic compound: Cr(NO₂)₃

• chromium nitrite
• chromium nitride
• chromium III nitride
• chromium III nitrite