Chapter 20, Problem 16QRT

Which Period 4 transition-metal ions are isoelectronic with

1. (a) Zn²⁺
2. (b) Mn²⁺
3. (c) Cr³⁺
4. (d) Fe³⁺

Interpretation Introduction

Interpretation:

Transition metal ion from period 4 that is isoelectronic with ${\text{Zn}}^{\text{2+}}$ has to be given.

Concept Introduction:

Isoelectronic means same electronic configuration.  An atom and an ion can be isoelectronic if they have same number of electrons in it.  This is because the electronic configuration will be same.  There will not be any change in atomic number or identity of the element or ion.

Explanation of Solution

Given ion is ${\text{Zn}}^{\text{2+}}$.  Zinc has an atomic number of 30.  The electronic configuration of zinc atom can be given as shown below.

    $\text{Zn: }1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10}$

Zinc atom loses two electrons to form ${\text{Zn}}^{\text{2+}}$ ion.  This can be represented as shown below.

    $\text{Zn}\to {\text{Zn}}^{2+}+2e^{-}$

The electronic configuration of ${\text{Zn}}^{\text{2+}}$ is given below.

    ${\text{Zn}}^{\text{2+}}\text{: }1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10}$

In period 4, the transition metal ion that is isoelectronic with ${\text{Zn}}^{\text{2+}}$ ion must also contain 28 electrons.  Copper is an element that has 29 electrons in its electronic configuration.  Copper loses one electron to form ${\text{Cu}}^{\text{+}}$ ion that has 28 electrons.  Electronic configuration of copper can be given as shown below.

    $\text{Cu: }1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^{10}$

Copper atom loses one electron to form ${\text{Cu}}^{\text{+}}$ ion.  This can be represented as shown below.

    $\text{Cu}\to {\text{Cu}}^{+}+1e^{-}$

The electronic configuration of ${\text{Cu}}^{\text{+}}$ is given below.

    ${\text{Cu}}^{\text{+}}\text{: }1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10}$

As the electronic configuration of ${\text{Zn}}^{\text{2+}}$ ion and ${\text{Cu}}^{\text{+}}$ ion are same, they both are said to be isoelectronic.  Thus ${\text{Cu}}^{\text{+}}$ is isoelectronic with ${\text{Zn}}^{\text{2+}}$.

Interpretation Introduction

Interpretation:

Transition metal ion from period 4 that is isoelectronic with ${\text{Mn}}^{\text{2+}}$ has to be given.

Concept Introduction:

Refer part (a).

Explanation of Solution

Given ion is ${\text{Mn}}^{\text{2+}}$.  Manganese has an atomic number of 25.  The electronic configuration of manganese atom can be given as shown below.

    $\text{Mn: }1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^5$

Manganese atom loses two electrons to form ${\text{Mn}}^{\text{2+}}$ ion.  This can be represented as shown below.

    $\text{Mn}\to {\text{Mn}}^{2+}+2e^{-}$

The electronic configuration of ${\text{Mn}}^{\text{2+}}$ is given below.

    ${\text{Mn}}^{\text{2+}}\text{: }1s^2 2s^2 2p^6 3s^2 3p^6 3d^5$

In period 4, the transition metal ion that is isoelectronic with ${\text{Mn}}^{\text{2+}}$ ion must also contain 23 electrons.  Iron is an element that has 26 electrons in its electronic configuration.  Iron loses three electrons to form ${\text{Fe}}^{\text{3+}}$ ion that has 23 electrons.  Electronic configuration of iron can be given as shown below.

    $\text{Fe: }1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6$

Iron atom loses three electrons to form ${\text{Fe}}^{\text{3+}}$ ion.  This can be represented as shown below.

    $\text{Fe}\to {\text{Fe}}^{3+}+3e^{-}$

The electronic configuration of ${\text{Fe}}^{\text{3+}}$ is given below.

    ${\text{Fe}}^{\text{3+}}\text{: }1s^2 2s^2 2p^6 3s^2 3p^6 3d^5$

As the electronic configuration of ${\text{Mn}}^{\text{2+}}$ ion and ${\text{Fe}}^{\text{3+}}$ ion are same, they both are said to be isoelectronic.  Thus ${\text{Fe}}^{\text{3+}}$ is isoelectronic with ${\text{Mn}}^{\text{2+}}$.

Interpretation Introduction

Interpretation:

Transition metal ion from period 4 that is isoelectronic with ${\text{Cr}}^{\text{3+}}$ has to be given.

Concept Introduction:

Refer part (a).

Explanation of Solution

Given ion is ${\text{Cr}}^{\text{3+}}$.  Chromium has an atomic number of 24.  The electronic configuration of chromium atom can be given as shown below.

    $\text{Cr: }1s^2 2s^2 2p^6 3s^2 3p^6 4s^1 3d^5$

Chromium atom loses three electrons to form ${\text{Cr}}^{\text{3+}}$ ion.  This can be represented as shown below.

    $\text{Cr}\to {\text{Cr}}^{3+}+3e^{-}$

The electronic configuration of ${\text{Cr}}^{\text{3+}}$ is given below.

    ${\text{Cr}}^{\text{3+}}\text{: }1s^2 2s^2 2p^6 3s^2 3p^6 3d^3$

In period 4, the transition metal ion that is isoelectronic with ${\text{Cr}}^{\text{3+}}$ ion must also contain 21 electrons.  Vanadium is an element that has 23 electrons in its electronic configuration.  Vanadium loses two electrons to form ${\text{V}}^{\text{2+}}$ ion that has 21 electrons.  Electronic configuration of vanadium can be given as shown below.

    $\text{V: }1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^3$

Vanadium atom loses two electrons to form ${\text{V}}^{\text{2+}}$ ion.  This can be represented as shown below.

    $\text{V}\to {\text{V}}^{2+}+2e^{-}$

The electronic configuration of ${\text{V}}^{\text{2+}}$ is given below.

    ${\text{V}}^{\text{2+}}\text{: }1s^2 2s^2 2p^6 3s^2 3p^6 3d^3$

As the electronic configuration of ${\text{Cr}}^{\text{3+}}$ ion and ${\text{V}}^{\text{2+}}$ ion are same, they both are said to be isoelectronic.  Thus ${\text{V}}^{\text{2+}}$ is isoelectronic with ${\text{Cr}}^{\text{3+}}$.

Interpretation Introduction

Interpretation:

Transition metal ion from period 4 that is isoelectronic with ${\text{Fe}}^{\text{3+}}$ has to be given.

Concept Introduction:

Refer part (a).

Explanation of Solution

Given ion is ${\text{Fe}}^{\text{3+}}$.  Iron has an atomic number of 26.  The electronic configuration of iron atom can be given as shown below.

    $\text{Fe: }1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6$

Iron atom loses three electrons to form ${\text{Fe}}^{\text{3+}}$ ion.  This can be represented as shown below.

    $\text{Fe}\to {\text{Fe}}^{3+}+3e^{-}$

The electronic configuration of ${\text{Fe}}^{\text{3+}}$ is given below.

    ${\text{Fe}}^{\text{3+}}\text{: }1s^2 2s^2 2p^6 3s^2 3p^6 3d^5$

In period 4, the transition metal ion that is isoelectronic with ${\text{Fe}}^{\text{3+}}$ ion must also contain 23 electrons.  Manganese is an element that has 25 electrons in its electronic configuration.  Manganese loses two electrons to form ${\text{Mn}}^{\text{2+}}$ ion that has 23 electrons.  Electronic configuration of manganese can be given as shown below.

    $\text{Mn: }1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^5$

Manganese atom loses two electrons to form ${\text{Mn}}^{\text{2+}}$ ion.  This can be represented as shown below.

    $\text{Mn}\to {\text{Mn}}^{2+}+2e^{-}$

The electronic configuration of ${\text{Mn}}^{\text{2+}}$ is given below.

    ${\text{Mn}}^{\text{2+}}\text{: }1s^2 2s^2 2p^6 3s^2 3p^6 3d^5$

As the electronic configuration of ${\text{Fe}}^{\text{3+}}$ ion and ${\text{Mn}}^{\text{2+}}$ ion are same, they both are said to be isoelectronic.  Thus ${\text{Mn}}^{\text{2+}}$ is isoelectronic with ${\text{Fe}}^{\text{3+}}$.