Question

The five successive ionisation energies of the element are 800, 2427,3658,25024 and
2824 kJ/mole. The number of valence electrons is with reason​

Answer 1

Given : The five successive ionisation energies of the element are ; 800 , 2427 , 3658 , 25024 , 32824 kJ/mole.

To find : The number of Valence electrons.

solution : we know, ionisation energy is the minimum amount of energy required to remove an electron from outermost orbit of isolated gaseous atom.

we also know, a stable configured atom/species has required higher amount of energy to remove electrons. means, ionisation energy will be higher in case of stable configured atom/species.

here I.E₁ = 800 kJ/mol

I.E₂ = 2427 kJ/mol

I.E₃ = 3658 kJ/mol

I.E₄ = 25024 kJ/mol

I.E₅ = 32824 kJ/mol

here you can see that I.E₄ is much more higher than I.E₃. it means, when we remove 3rd electrons from an atom, it becomes stable configured species. so, there are three electrons in its outermost orbit.

Therefore number of valence electrons in the element is 3.