Chapter 18, Problem 20STP

To determine

To explain: the reason why elements in group 4, which have four electrons in the outer energy level, are unlikely to lose all of the electrons in the outer energy level.

Explanation of Solution

Introduction:

The elements present in group 3-12 are called d-block elements or transition elements. The last electrons in transition elements enter the d sub-shell called a d-block element.

The first element present in group 4 is titanium. Its atomic number is 22.

So, its electronic configuration is $\left[\text{Ar}\right]{\text{3d}}^{\text{2}}{\text{4s}}^{\text{2}}$ . Thus, it has 4 electrons in its valence shell. Titanium shows two types of oxidation state that is, +2 and +5. During the formation of the +2 oxidation number, titanium loses 2 electrons from 4s sub-shell and forms ${\text{Ti}}^{\text{+2}}$ . Here, ${\text{Ti}}^{\text{+2}}=\left[\text{Ar}\right]{\text{3d}}^{\text{2}}$ .

When ${\text{Ti}}^{\text{+4}}$ is formed, then all the 4 electrons are lost and the configuration is $\left[\text{Ar}\right]{\text{3d}}^{\text{0}}{\text{4s}}^{\text{0}}$ .

However, only 2 electrons are lost during normal conditions. Thus, it shows that the oxidation number is +2.

Conclusion:

Hence, group 4 elements have 4 outermost electrons due to keeping themselves in a stable configuration.