Chapter U1.22, Problem 3E

Interpretation Introduction

Interpretation:

The name of the ionic compounds needs to be determined.

Concept introduction:

Some ionic species are composed of more than one atom. These are called polyatomic ions. The entire cluster of atoms shares the charge on a polyatomic ion. Each polyatomic ion has a charge that is used when writing formulae of the compound.

Answer to Problem 3E

The following table shows names of ionic compounds.

Formulae	Name of compounds
a. NH4Cl	Ammonium chloride
K2SO4	Potassium sulfate
c. Al(OH)3	Aluminium hydroxide
d. MgCO3	Magnesium carbonate

Explanation of Solution

Given information:

Formulae of some ionic compounds are given.

Formulae

a. NH4Cl

b. K2SO4

c. Al(OH)3

d. MgCO3

Each polyatomic ion has a unique name that is used while naming the compound. Ionic compounds with polyatomic ions follow certain naming rules. Each polyatomic ion has its own name such as hydroxide for (OH^-), nitrate for (NO₃^-), carbonate for (CO₃^2-), sulfate for (SO₄^2-) etc. While naming the compounds, the polyatomic ion name is added either in the beginning or end of the chemical name. Cation is named first and then anion.

1. NH₄Cl - Here ammonium (NH₄ ⁺ ) is the polyatomic cation. So the compound is named as ammonium chloride.
2. K₂SO₄ - Here sulfate (SO₄^2-) is the polyatomic anion. So the compound is named as potassium sulfate.
3. Al(OH)₃ - Here hydroxide (OH^-) is the polyatomic anion. So the compound is named as aluminium hydroxide.
4. MgCO₃ - Here carbonate (CO₃^2-) is the polyatomic anion. So the compound is named as magnesium carbonate.

Conclusion

Ionic compounds with polyatomic ions follow certain naming rules. Polyatomic ions are a group of atoms bonded together.