Question

The decreasing order of the first ionization energy of group 16 elements is:

• A. $O>S>Se<Te>Po$
• B. $O>S>Se>Te>Po$
• C. $O<S<Se<Te<Po$
• D. None of the above

Answer 1

The correct option is B $O>S>Se>Te>Po$

As we go down the group, the size of the atoms increases. In general, this also implies that the distance between the nucleus and the valence electrons increases. As we move farther from the nucleus the electrostatic force of attraction between the nucleus and the valence electrons decreases due to the shielding effect of the inner electrons. The greater the number of inner electrons, the higher is the effect of shielding. Thus, Ionization energy down the group in group 16 decreases gradually because valence shell electron can easily be removed with the increase in size of the element.