what is diagonal relationship?explain its causes.
Answers
A diagonal relationship is said to exist between certain pairs of diagonally adjacent elements in the second and third periods of the periodic table.
Such a relationship occurs because moving left to right and descending top to bottom in the periodic table have opposing effects.
For example, on moving from left to right across a period, there is an increase in electronegativity while, moving down in the group there is a decrease in electronegativity. Therefore, on moving diagonally, the two opposing tendencies almost cancel out and the electronegativity values remain almost same. Thus diagonal pairs have many similar properties.
So, it can be concluded that the similarity of properties such as electronegativity, ionization energy, size etc. between the diagonal elements is the cause of diagonal relationship.
ANSWER
Diagonal Relationship
1)The properties of elements of a group in the second period is similar to the second element of next group. This is known as Diagonal Relationship.
Example =>
Second Period=Li, Be
Third period =Na, Mg
-Here, Li and Mg has similar properties and has a Diagonal Relationship
-Similarly, Na and Be has similar properties and has Diagonal Relationship.
2)But this only exist between some pairs of diagonally adjacent elements in the second and third periods of the periodic table of elements.
Causes for Diagonal Relationship are=>
i) Due to similar ionic size.
ii) Similar capacity to gain electrons.
iii) Similarity in polarising power.