Chapter 4, Problem 4.38QP

(a)

Interpretation Introduction

Interpretation: The oxidation number of alkali and alkaline earth metals in their compounds has to be given.

Concept introduction:

Alkali metals are the elements found in group I of the periodic table, they are also called as active elements.

Alkali metals ($Li,Na,K,Rb,Cs\text{}andFr$ ) readily combine with the group 17 elements. And they form hydroxides too.

Group II elements are called alkaline earth metals $\left(Be,Mg,Ca,Sr,Ba,andRa\right)$. These elements are slightly less reactive than the alkali metals.

• The number of electrons an atom tends to give up or gain in a chemical reaction is called oxidation number.
• Rules for assigning oxidation number

1. 1. 1. The oxidation number of the atom of an uncombined element is zero.
   2. 2. The sum of the oxidation numbers of all atoms in a compound must equal to the total charge on the species.
   3. 3. Hydrogen has an oxidation number of +1 unless it is combined with metals, in which case it has an oxidation number of -1.
   4. 4. Oxygen has an oxidation number of -2, except in peroxides where it is -1 and in $O{F}_2$ where it is +2.

(b)

Interpretation Introduction

Interpretation:   It should be determined that the highest oxidation number of elements in groups 3A to 7A.

Concept introduction:

• The number of electrons an atom tends to give up or gain in a chemical reaction is called oxidation number.
• Rules for assigning oxidation number

1. 1. 1) The oxidation number of the atom of an uncombined element is zero.
   2. 2) The sum of the oxidation numbers of all atoms in a compound must equal to the total charge on the species.
   3. 3) Hydrogen has an oxidation number of +1 unless it is combined with metals, in which case it has an oxidation number of -1.
   4. 4) Oxygen has an oxidation number of -2, except in peroxides where it is -1 and in $O{F}_2$ where it is +2.