Chapter 4, Problem 1STP

Interpretation Introduction

Interpretation:

The number of compounds which are correctly named is to be chosen.

Concept introduction:

To name a compound, certain rules are followed. The given compounds are binary compounds.

Binary compounds are of three types:

• Type-I: Compound in which a metal forms ionic bond with a non-metal and the metal can form only one type of ions.
• Type-II: Compound in which a metal forms ionic bond with a non-metal and the metal can form more than one type of ions.
• Type-III: Compound in which a non-metal forms bond with a non-metal.

There is one another type of compound in which metal is bonded with a polyatomic ion

Rules for naming these compounds:

Type-I:

1. Name of metal cation is written as name of element.
2. Name of anion is written using root name and adding ‘ide’ to it.
3. Writing these names in the same sequence gives the name of compound.

Type-II:

1. Name of metal cation is written as name of element followed by charge carried by it in roman numerals in bracket.
2. Name of anion is written using root name and adding ‘ide’ to it.
3. Writing these names in the same sequence gives the name of compound.

Type-III:

1. The name of the first element is written as given in the periodic table.
2. Second element in anionic form and prefixes are used to denote the number of atoms. Like, prefix mono is not used for 1element.

When metal is bonded with polyatomic ion, rules are similar to ionic binary compounds.

Answer to Problem 1STP

A

Explanation of Solution

$N{a}_{2}S{O}_4$ is a compound of metal with polyatomic ion “sulphate” and sodium is a metal of type-I. So its name is Sodium sulphate.

$CaC{O}_3$ is a compound of metal with polyatomic ion “carbonate” and calcium is a metal of type-I. So its name is Calcium carbonate.

$PC{l}_5$ is a binary compound of non-metal with non-metal. So, its name is phosphorus pentachloride.

$CoO$ is compound of oxide ion with metal of type-II. So, its name is cobalt(II) oxide.

Conclusion

Applying the rules suggest all the compounds are named correctly. So option A is correct.