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what is diagonal relationship?explain its causes.

On moving diagonally in the modern periodic table the elements show certain similarities.

This is due to the fact that on moving across a period from left to right electropositivity of the atom decreases.On the other hand on moving down the group electropositivity increases. These two factors work in opposite direction. Hence the elements that are present diagonally to each other have similar properties.

Diagonal relationship is more noticeable in the second and third period of the modern periodic table.It is shown as under:-

As a result of diagonal relationship the physical properties such as the atomic size, electronegativity, density etc. and chemical properties of compounds such as reaction with water, nitrogen, decomposition reactions etc. are similar.
For example: The similarities between Li and Mg as a result of diagonal relationship are as follows:
  • Both are harder and lighter than the other elements in the respective groups.
  • Both react slowly with water; oxides of both are less soluble in water; hydroxides of both decompose on heating.
  • Both form nitrides (Li3N and Mg3N2) by directly reacting with nitrogen.
  • Both do not form superoxide.
  • On heating, carbonates of both give oxides and CO2; hydrogen carbonates of both do not exist as solid.
  • Chlorides of both (LiCl, MgCl2) are soluble in ethanol, deliquescent, and crystallize as hydrates (LiCl.2H2O, MgCl2.8H2O).

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On moving diagonally in the modern periodic table the elements show certain similarities.

This is due to the fact that on moving across a period from left to right electropositivity of the atom decreases.On the other hand on moving down the group electropositivity increases. These two factors work in opposite direction. Hence the elements that are present diagonally to each other have similar properties.

Diagonal relationship is more noticeable in the second and third period of the modern periodic table.It is shown as under:-

 

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.

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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.

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ok thanx ishan

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