Question

The cause of diagonal relationship is due to similar value of:
A. ionisation energy
B. electron affinity
C. polarising power
D. electronegativity

Answer 1

Hint: To solve this question, first we need to understand the concepts of diagonal relationships. Diagonal relationship occurs due to the different ways in which the atomic properties vary as we move down groups and across the periods in the Periodic Table. In addition to the period and group relationships, there are elements of the p and s-block that also show diagonal relationships.

Complete step by step answer:
Diagonal relationship is formed due to the identical size of ions. As we move towards right across a period in the periodic table, then the size of the atom reduces, and when we move downward across a group then the size of the atoms gradually increases. Likewise, as we move towards right in a period, then the elements will tend to become more electronegative, and when we go downward a group then the element will become more electropositive.
Now, we get to know that, as both of these factors work in opposite directions. Hence, those elements which are present in a diagonal to each other and these diagonal elements possess similar properties like density, atomic size, electronegativity, polarizing power and chemical properties of different compounds and elements.
So, the cause of diagonal relationship is due to the similarity of electronegativity and polarising power.
$\therefore $The option C and D is the correct answer..

Note:
We must know that the factors that affect the electronegativity and polarising power are nuclear charge, atomic size, and shielding or screening effect. Diagonal relationships exist between Lithium and Magnesium, Boron and Silicon, and Beryllium and Aluminium. Also, the elements of the p and s-block possess diagonal relationships.