Question

Consider following ionisation steps:

$M\left(g\right)\to M^{+}\left(g\right)+e^{-};\Delta H=100eV$
$M\left(g\right)\to M^{2+}\left(g\right)+2e^{-};\Delta H=250eV$

Select correct statement(s):

• A. $(IE{)}_1$ or M(g) is 100 eV
• B. $(IE{)}_1$ or M${}^{+}$(g) is 150 eV
• C. $(IE{)}_2$ or M(g) is 250 eV
• D. $(IE{)}_2$ or M(g) is 150 eV

Answer 1

Answer: (A), (B), (D)

$(IE{)}_1$ or M(g) is 100 eV
$(IE{)}_1$ or M${}^{+}$(g) is 150 eV
$(IE{)}_2$ or M(g) is 150 eV

The first ionization energy is the energy it takes to remove one electron from an atom, the second ionization energy is the energy it takes to remove a second electron from the atom, and so on.

$M\left(g\right)\to M^{+}\left(g\right)+e^{-};\Delta H=100eV$

$M\left(g\right)\to M^{2+}\left(g\right)+2e^{-};\Delta H=250eV$

Energy required to remove first electron from M is 100 eV so the $(IE{)}_1$ or $M\left(g\right)$ is $100$ eV.

Energy required to remove two electrons from $M$ is $250$ eV so we can say that energy required to remove an electron from $M^{+}$ is $150$ eV. So the$(IE{)}_1$ of M${}^{+}$(g) is $150$ eV.

Energy required to remove the second electron from $M$ is $150$ eV so the $(IE{)}_2$ or $M\left(g\right)$is $150$ eV.