Question

Which out of $Cu^{2+}$, $Fe^{2+}$, $Cr^{3+}$ has highest para–magnetism and why? ( Given At.No. Cu = 29, Fe = 26, Cr = 24)

Answer 1

Given,  

Atomic Number of Copper Cu = 29

Atomic Number of Iron Fe = 26

Atomic Number of Chromium Cr = 24

The electronic configuration of ${ Cu }^{ 2+ }= 1{ s }^{ 2 }2{ s }^{ 2 }2{ p }^{ 6 }3{ s }^{ 2 }3{ p }^{ 6 }3{ d }^{ 9 }.$

Since one electron is unpaired, it exhibit paramagnetism.

The electronic configuration of ${ Fe }^{ 2+ } = 1{ s }^{ 2 }2{ s }^{ 2 }2{ p }^{ 6 }3{ s }^{ 2 }3{ p }^{ 6 }3{ d }^{ 6 }$.

Since four electron are unpaired, it exhibit para-magnetism.

The electronic configuration of ${ Cr }^{ 3+ }= 1{ s }^{ 2 }2{ s }^{ 2 }2{ p }^{ 6 }3{ s }^{ 2 }3{ p }^{ 6 }3{ d }^{ 5 }4{ s }^{ 1 }$.

Since here three electrons are unpaired, it also exhibit para-magnetism.

${Fe }^{ 2+}$ has the highest para – magnetism, since it has four lone pair of electrons.

Answer 2

Given,

Atomic Number of Copper Cu = 29

Atomic Number of Iron Fe = 26

Atomic Number of Chromium Cr = 24

The electronic configuration of { Cu }^{ 2+ }= 1{ s }^{ 2 }2{ s }^{ 2 }2{ p }^{ 6 }3{ s }^{ 2 }3{ p }^{ 6 }3{ d }^{ 9 }.Cu

2+

=1s

2

2s

2

2p

6

3s

2

3p

6

3d

9

.

Since one electron is unpaired, it exhibit paramagnetism.

The electronic configuration of { Fe }^{ 2+ } = 1{ s }^{ 2 }2{ s }^{ 2 }2{ p }^{ 6 }3{ s }^{ 2 }3{ p }^{ 6 }3{ d }^{ 6 }Fe

2+

=1s

2

2s

2

2p

6

3s

2

3p

6

3d

6

.

Since four electron are unpaired, it exhibit para-magnetism.

The electronic configuration of { Cr }^{ 3+ }= 1{ s }^{ 2 }2{ s }^{ 2 }2{ p }^{ 6 }3{ s }^{ 2 }3{ p }^{ 6 }3{ d }^{ 5 }4{ s }^{ 1 }Cr

3+

=1s

2

2s

2

2p

6

3s

2

3p

6

3d

5

4s

1

.

Since here three electrons are unpaired, it also exhibit para-magnetism.

{Fe }^{ 2+}Fe

2+

has the highest para – magnetism, since it has four lone pair of electrons.