1. Tardigrade
  2. Question
  3. Chemistry
  4. Consider the following ionization enthalpies of two elements 'A' and 'B' Element <td colspan=3>Ionization enthalpy (kJ/mol) 1st 2nd 3rd A 899 1757 14847 B 737 1450 7731 . Which of the following statements is correct ?

Q. Consider the following ionization enthalpies of two elements 'A' and 'B'
Element Ionization enthalpy (kJ/mol)
1st 2nd 3rd
A 899 1757 14847
B 737 1450 7731
.
Which of the following statements is correct ?

 3610  209 JEE MainJEE Main 2017Classification of Elements and Periodicity in Properties Report Error

Solution:

Both ′A′ and ′B′ belong to group-2 where ′B′ comes below ′A′.
We observe that there is a huge difference in second and third ionization energies. This is characteristic of alkaline earth metals. They lose 2 valence electrons to form a dipositive ion with stable electronic configuration. Removal of the third electron will require very high energy as it will break the stable noble gas configuration.
On moving down the group, the ionisation energy decreases. Since first ionisation energy of B is lower than that of A, ′B′ comes below ′A′