Chapter 8, Problem 8.111SP

Interpretation Introduction

Interpretation:

Reason for why the first ionization energy of helium is less than twice the ionization energy of hydrogen, but the second ionization energy of helium is greater than twice the ionization energy of hydrogen has to be explained.

Concept Introduction:

First ionization energy: The ionization energy is the minimum energy required to remove the electron from an isolated atom which is in the gaseous state results to give gaseous ion with one positive charge.

Second ionization energy: The minimum energy needed to remove an electron from a unipositive gaseous ion to form a dipositive ion in the ground state is known as second ionization energy.

Effective nuclear charge $Z_{\text{eff}}$ is the net nuclear charge experienced by an electron when the whole nuclear charge and the shielding of other electrons are considered.

According to Coulomb’s Law,

• The potential energy (E) experienced between two ions increases directly with the product of their charges,(Qcation.Qanion)
• The potential energy experienced between two ions is inversely proportional to the distance of between the ions, (r).

Coulomb’s Law can be written as:

$E=k\frac{Q_{cation}{Q}_{anion}}{r}$