Which of the following relations is correct with respect to
first (I) and second (II) ionization potentials of sodium and
magnesium?
(a) IMg = IINa (b) IMg < IINa
(c) INa > IMg (d) IINa > IIMg
Answers
The option is (d) is correct for ionization potential of sodium and magnesium.
(d) IINa > IIMg
Explanation:
As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases.
As we move down the group ionization energy decreased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus the ionization energy from top to bottom decreases because it becomes easier to remove the electron.
when one electron is removed from sodium and magnesium both gets the positive charge but sodium also get the noble gas electronic configuration which is more stable. That's why it becomes difficult to remove the another electron from sodium as compared the magnesium. Thus second ionization potential of sodium is greater than magnesium.