Chapter 6, Problem 78A

(a)

Interpretation Introduction

Interpretation: To write the symbol of cations and anions that are isoelectronic with krypton.

Concept introduction:

When two atoms, ions, or molecules have equal electronic structures or have the same electron count, then they are said to be isoelectronic species.

Answer to Problem 78A

  ${\text{Rb}}^{+}$ , ${\text{Br}}^{-}$

Explanation of Solution

The atomic number of Kryton is 36 which means no. of electrons in krypton is 36.

Atomic no. of bromine s 35. When it takes one electron and forms ${\text{Br}}^{-}$ , no. of electrons becomes 36. So, ${\text{Br}}^{-}$ is isoelectronic with Krypton.

The atomic number of Rubidium (Rb) is 37. It is an alkali metal and easily loses one electron to form ${\text{Rb}}^{+}$ . After losing one electron, no. of electrons becomes 36. So, ${\text{Rb}}^{+}$ is isoelectronic with Krypton.

(b)

Interpretation Introduction

Interpretation: The possibility of cations of the same period to be isoelectronic with the anion of the same period is to be determined.

Concept introduction:

When two atoms, ions, or molecules have equal electronic structures or have the same electron count, then they are said to be isoelectronic species.

Answer to Problem 78A

No

Explanation of Solution

No, a cation can't be isoelectronic with an anion in the same period. This is because across the period nuclear charge and no. of electron increases. Elements of left size tend to lose electrons and elements of the right side tend to gain an electron.

Thus, a cation can't be isoelectronic with an anion in the same period.