Chapter U1.21, Problem 4E

Interpretation Introduction

Interpretation:

Examples of six ionic compounds with a metal - to - nonmetal ratio of 1:1 are to be given and total number of valence electrons in each compound has to be specified. Also the compound names have to be given.

Concept introduction:

Ionic compounds are formed between metals and nonmetals. There are about 50 metals and 15 nonmetals which combine in a variety of ways to form large number of ionic compounds. Valence electrons are electrons in the outermost orbit of an atom.

Answer to Problem 4E

The following table shows ionic compounds formed with metals to nonmetals ratio of 1:1.

Metal	Nonmetal	Compound	Number of valence electrons
Na	Cl	NaCl-sodium chloride	8
Na	Br	NaBr - sodium bromide	8
K	Cl	KCl - potassium chloride	8
K	Br	KBr - potassium bromide	8
Li	Cl	LiCl - lithium chloride	8
Li	I	LiI - lithium iodide	8

Explanation of Solution

Given information:

Metal to nonmetal ratio in ionic compounds is 1:1.

For a compound to have metal to nonmetal ratio of 1:1 the metal must have one valence electron and the nonmetal must have seven valence electrons so that the total number of valence electrons in the compound is 8. So the metal must be from group 1A and nonmetal must be from group 7A. Metals of group 1A are sodium, potassium, lithium, rubidium, caesium and francium. Nonmetals of group 7 A are halogens like fluorine, chlorine, bromine, iodine and astatine. The charges on metals are + 1 and nonmetals are -1 which add up to zero.

To name the compound, metal name comes first and then nonmetal name changed to “-ide”.

The ionic compounds possible are therefore sodium chloride, sodium bromide, sodium iodide, sodium fluoride, potassium chloride, potassium bromide, lithium bromide, lithium chloride etc.

Conclusion

Metals and nonmetals combine to form ionic compounds. Such compounds are called salts.