Chapter 4.11, Problem 5QQ

Interpretation Introduction

Interpretation:

Among the given options, the name of a compound ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}\text{S}$ has to be chosen.

Concept Introduction:

Chemical formulas and names for ionic compounds containing polyatomic ions:

Ionic compounds containing positive and negative charges present and those must add to get resultant charges as zero.  If more than one polyatomic ion is present in a compound, the chemical formula can be written as a polyatomic ion is enclosed in parentheses and a subscript, placed outside of the parenthesis.

Example- ${\text{Fe(OH)}}_{\text{3}}$.

Sometimes same element is present in two different locations.  For example, ${\text{NH}}_{\text{4}}{\text{NO}}_{\text{3}}$- in this chemical formula “$\text{N}$” is present in two different locations as ${\text{NH}}_{\text{4}}^{\text{+}}{\text{ and NO}}_{\text{3}}^{\text{-}}$ ions.

The following rules are used for naming of polyatomic ions:

• If a positive polyatomic ion is present, its name is substituted for that of the metal.
• If a negative polyatomic ion is present its name is substituted for that of the nonmetal stem name and the “ide” suffix.
• If both positive and negative polyatomic ions are present, dual name – substitution occurs, and the resulting name includes just the names of the polyatomic ions.