Question

For $X^{5+}$ ion, the successive electron affinities (in eV) are 289.7, 270.9, 30.1, 17.9 and 8.3. The expected number of electrons in the outermost shell of X atom is

Answer 1

Electron affinities and ionization enthalpy are same in magnitude

$X\to X^{+}+e^{-}$ 8.3

$X^{+}\to X^{2+}+e^{-}$ 17.9

$X^{2+}\to X^{3+}+e^{-}$ 30.1

$X^{3+}\to X^{4+}+e^{-}$ 270.9

$X^{4+}\to X^{5+}+e^{-}$ 289.7

Since the energy required to remove the fourth electron is substantially high, we can conclude that only 3 electrons are present in outermost shell.