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Question 1

Electronic Configurations of Transition Metals

Answer 1

Sc: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹
Ti: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²
V: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d³
Cr: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵
Mn: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵
Fe: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶
Co: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁷
Ni: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁸
Cu: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d¹⁰
Zn: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰

Question 2

Electronic Configurations of Transition Metal Ions (3+)

Answer 2

Sc³⁺: [Ar] 4s⁰ 3d⁰
Ti³⁺: [Ar] 4s⁰ 3d¹
V³⁺: [Ar] 4s⁰ 3d²
Cr³⁺: [Ar] 4s⁰ 3d³
Mn²⁺: [Ar] 4s⁰ 3d⁵
Fe³⁺: [Ar] 4s⁰ 3d⁵
Co²⁺: [Ar] 4s⁰ 3d⁷
Ni²⁺: [Ar] 4s⁰ 3d⁸
Cu²⁺: [Ar] 4s⁰ 3d⁹
Zn²⁺: [Ar] 4s⁰ 3d¹⁰

Question 3

Why is Zinc not a Transition Metal?

Answer 3

Zinc can only form a +2 ion, and Zn²⁺ has a complete d orbital, not meeting the criteria of having an incomplete d orbital.

Question 4

Complex Formation

Answer 4

Complex: A central metal ion surrounded by ligands.
Ligand: An atom, ion, or molecule donating a lone electron pair.
Co-ordinate bonding involves the sharing of electrons from only one bonding atom.
Co-ordination number: The number of co-ordinate bonds formed to a central metal ion.

Question 5

Substitution Reactions

Answer 5

Ligands can be monodentate (e.g., H₂O, NH₃, Cl⁻), bidentate (e.g., NH₂CH₂CH₂NH₂, C₂O₄²⁻), or multidentate (e.g., EDTA⁴⁻).
Ligands NH₃ and H₂O can act as monodentate ligands.
Ligand exchange can occur without a change in coordination number.

Question 6

Reactions with Chloride Ions

Answer 6

Addition of chloride ions can lead to ligand substitution, changing the coordination number.
Example: [Cu(H₂O)₆]²⁺ + 4Cl⁻ → [CuCl₄]²⁻ + 6H₂O (tetrahedral shape)
Addition of conc HCl to aqueous ions of Cu and Co leads to a change in coordination number from 6 to 4.
Example: [Co(H₂O)₆]²⁺ + 4Cl⁻ → [CoCl₄]²⁻ + 6H₂O (tetrahedral shape)

Question 7

Bidentate Ligands

Answer 7

Bidentate ligands have two atoms with lone pairs and can form two coordinate bonds per ligand.
Examples:
Ethanedioate ion: C₂O₄²⁻
Ethane-1,2-diamine: NH₂CH₂CH₂NH₂

Question 8

Haem - Iron(II) Complex

Answer 8

Haem is an iron(II) complex with a multidentate ligand.
Example: [Cr(NH₂CH₂CH₂NH₂)₃]³⁺ (coordination number of 6)

Question 9

EDTA Complex Formation

Answer 9

[Cu(H₂O)₆]²⁺ + EDTA⁴⁻ → [Cu(EDTA)]²⁻ + 6H₂O
EDTA⁴⁻ has six donor sites (4O and 2N) and forms a 1:1 complex with metal(II) ions.

Question 10

Bidentate Complex with Ethanedioate Ligands

Answer 10

Example: [Cr(C₂O₄)₃]³⁻ (coordination number of 6)

Question 11

Partial Substitution of Ethanedioate Ions

Answer 11

[Cu(H₂O)₆]²⁺ + 2C₂O₄²⁻ → [Cu(C₂O₄)₂(H₂O)₂]²⁻ + 4H₂O
Partial substitution of ethanedioate ions can occur when added to a solution containing aqueous copper(II) ions.

Question 12

Multidentate Ligands

Answer 12

Multidentate ligands (e.g., EDTA⁴⁻) can form six coordinate bonds per ligand.

Question 13

Reactions Involving Bidentate Ligands

Answer 13

[Cu(H₂O)₆]²⁺ + 3NH₂CH₂CH₂NH₂ → [Cu(NH₂CH₂CH₂NH₂)₃]²⁺ + 6H₂O
[Cu(H₂O)₆]²⁺ + 3C₂O₄²⁻ → [Cu(C₂O₄)₃]⁴⁻ + 6H₂O

Question 14

Partial Substitution of Ethanedioate Ions in Copper Complex

Answer 14

[Cu(H₂O)₆]²⁺ + 2C₂O₄²⁻ → [Cu(C₂O₄)₂(H₂O)₂]²⁻ + 4H₂O

Question 15

Coordination Bond in Haemoglobin and Toxicity of CO

Answer 15

Oxygen forms a co-ordinate bond to Fe(II) in haemoglobin, enabling oxygen transport in the blood.
CO is toxic because it forms a strong coordinate bond with haemoglobin, replacing oxygen and preventing proper oxygen transport.