Chapter 6, Problem 40A

(a)

Interpretation Introduction

Interpretation: Between lithium and boron, the one with greater first ionization energy is to be identified.

Concept introduction:

The first ionization energy is the energy needed for the removal of the outermost electron from the neutral gaseous atom.

  $X\left(g\right)+I{E}_1\to X^{+}\left(g\right)+e^{-}$

Answer to Problem 40A

Boron

Explanation of Solution

Across the period or from left to right, the first ionization energy increases because of a decrease in atomic radius. Lithium is present in group 1 and boron is present in group 13. Boron is present right to lithium. Thus, the first ionization energy of boron is greater than lithium.

(b)

Interpretation Introduction

Interpretation: Between magnesium and strontium, the one with greater first ionization energy is to be identified.

Concept introduction:

The first ionization energy is the energy needed for the removal of the outermost electron from the neutral gaseous atom.

  $X\left(g\right)+I{E}_1\to X^{+}\left(g\right)+e^{-}$

Answer to Problem 40A

Magnesium

Explanation of Solution

The ionization energy is inversely related to the atomic radius. The higher the atomic radius, the lower will be the ionization energy.

Down the group, atomic radius increases. Strontium and magnesium are placed in the same group (group 2). Strontium is present below the magnesium. So, the atomic radius of strontium is larger than magnesium.

Thus, the first ionization energy of magnesium is greater than the first ionization of strontium.

(c)

Interpretation Introduction

Interpretation: Between cesium and aluminum, the one with greater first ionization energy is to be identified.

Concept introduction:

The first ionization energy is the energy needed for the removal of the outermost electron from the neutral gaseous atom.

  $X\left(g\right)+I{E}_1\to X^{+}\left(g\right)+e^{-}$

Answer to Problem 40A

Aluminum

Explanation of Solution

The ionization energy is inversely related to the atomic radius. The higher the atomic radius, the lower will be the ionization energy.

Down the group, atomic radius increases while decreasing when moving from left to right. Cesium is placed below aluminum. The element cesium is also placed left to aluminum. Thus, the first ionization energy of aluminum is greater than cesium.