Question

Which group in p-block elements shows highest positive oxidation state?
A. $16$
B. $17$
C. $18$
D. $15$

Answer 1

Oxidation state is also known as oxidation number. It defines the ability to transfer electrons by an element for the formation of bonds between the atoms. Oxidation state is of two types-positive and negative.

Complete step by step answer:
When the oxidation number or state is positive, it indicates that the element loses its electrons. When the oxidation number or state is negative, it indicates that the element gains electrons. This is based on the electronegativity of the element. Electronegativity is the ability of an atom to pull electrons towards itself.
There are several elements which show positive oxidation state. Generally, metals show positive oxidation state in their corresponding compounds. For example, sodium shows $+ 1$ oxidation state in ${{NaCl}}$. Generally, s-block elements show positive oxidation state.
But in the case of p-block elements, it is different. We have to find the group in p-block elements which show the highest positive oxidation state.
Group $16$ element, i.e. sulfur has electronic configuration ${{1}}{{{s}}^2}{{2}}{{{s}}^2}{{2}}{{{p}}^6}{{3}}{{{s}}^2}{{3}}{{{p}}^4}$, i.e. $2,8,6$.
Group $17$ element, i.e. chlorine has electronic configuration ${{1}}{{{s}}^2}{{2}}{{{s}}^2}{{2}}{{{p}}^6}{{3}}{{{s}}^2}{{3}}{{{p}}^5}$, i.e. $2,8,7$
Group $18$ element, i.e. argon has electronic configuration ${{1}}{{{s}}^2}{{2}}{{{s}}^2}{{2}}{{{p}}^6}{{3}}{{{s}}^2}{{3}}{{{p}}^6}$, i.e. $2,8,8$
Group $15$ element, i.e. phosphorus has electronic configuration ${{1}}{{{s}}^2}{{2}}{{{s}}^2}{{2}}{{{p}}^6}{{3}}{{{s}}^2}{{3}}{{{p}}^3}$, i.e. $2,8,5$
From the above data, it is obvious that the more electrons are occupied in group $18$. When the elements in the group $18$ form compounds with more electronegative elements like oxygen, fluorine etc. they form oxidation states like $+ 4, + 6, + 7, + 8$.
So we can say that group $18$ elements from the highest positive oxidation states.

So, the correct answer is Option C.

Note: Similar to the p-block elements, when transition metals form compounds with most electronegative elements like oxygen, fluorine etc. they have the highest oxidation states. They also have the ability to form low oxidation states when they form complexes with ligands like carbonyl groups.