Question

Which of the following trends is indirectly proportional to effective nuclear charge, Zeff

-ionization energy
-electron affinity
-atomic size
-all answers are correct

Answer 1

Periodic trends provides information about an element’s properties. One major trends in the periodic table is the atomic size, which is indirectly proportional to effective nuclear charge. The atomic size gradually decreases from left to right across a periodic table because all electrons are added to the same shell. At the same time, protons are also added to the nucleus, making it more positively charged.

Due to this, there is a greater nuclear attraction; the effect of increasing proton number is greater than that of the increasing electron number, which means that there is a strong attraction of nucleus manifested by pulling the atom's shell closer to the nucleus. Then, the valence electrons are seized closer towards the nucleus of the atom, which resulted to the decrease in atomic radius.

Answer 2

Answer : Option C) Atomic Size

Explanation : The atomic radius of the elements is found to be decreasing if we go from left to right in the modern periodic table. Accordingly,
`Z_(eff)` increases as the number of shielding electrons present in the atomic nucleus of the periodic elements which lies in the same row remains constant while the number of protons in each atomic shell increases.

The effective nuclear charge
`Z_(eff)` of an atom is defined as the net positive charge which is felt by the valence electron of the atomic element.

When
`Z_(eff)` is observed to decrease, it is seen that the atomic radius grows in size. So, it explains the inverse relationship between both. This phenomenon occurs, because there is more screening of the electrons from the nucleus taking place, which is observed due to decrease the attraction between the electron and the nucleus.