Question

Would you expect the first ionization enthalpies for two isotopes of the same element to be the same or different? Justify your answer.

Answer 1

The first ionization enthalpies for two isotopes of the same element are expected to be the same.

Reason (Conceptual)

Ionization enthalpy depends mainly on:

• Number of protons in the nucleus (nuclear charge).
• Number of electrons and their arrangement (electronic configuration).

Isotopes of an element have:

• The same atomic number \(Z\) (same number of protons).
• The same number of electrons and the same electronic configuration.
• They differ only in the number of neutrons (mass number), which does not significantly affect the energy needed to remove an electron.

Key Idea in LaTeX

For any isotope of a given element: \[ \text{Ionization enthalpy} \;\propto\; f(\text{nuclear charge},\ \text{electron configuration}) \] \[ \text{Neutrons do not change } Z \text{ or the electron configuration} \] Therefore, the first ionization enthalpy of two isotopes of the same element is expected to be the same.