Effective nuclear charge `(Z_(eff))` is the net attractive force on electrons under consideration and is equal to:
`Z_(eff) = Z - sigma` (nuclear charge - screening constant). `Z_(eff)` or `sigma` is calculated by Slater's formula, as given.
If one electrons is present in the outermst orbit, there will be no screening in that orbital. Each electrons contribute, `0.35` (total electrons minus one electron) present in the outermost shell.
A contribution of `0.85` for each electrons is taken in the `(n - 1)th` shell.
Which of the following statement is wrong?

Options

A. The number of lobes in `f`-orbitals are `8`.
B. `IE_(1)` of elements increases along the period.
C. `IE_(1)` of the group `3` elements is more than that of the group `2` elements.
D. `IE_(1), IE_(2)` and `IE_(3)` of an elemnt are `9.5, 18.5` and `154.4 eV`. Predict that the element has either two `s`-electrons or two `p`-electrons in the valence shell.

Answer

C

Explanation

Statement (c ) is wrong. `IE_(1)` of group `3` element is less than that of group `2` elements due to penetration effect.