Transition Metals

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Questions and Answers

What oxidation state does Zn typically exhibit in compounds?

+2 (correct)

Which of the following statements about complex ions is true?

Complex ions do not require ligands.

Complex ions are always neutral.

A complex ion retains its identity in solution. (correct)

Complex ions cannot form with transition metals.

Which oxidation state of iron is more stable?

Fe3+ (correct)

Fe2+

Fe0

Both Fe2+ and Fe3+ are equally stable

What is the charge of the complex ion in [Ag(NH3)2]+?

+1 Signup and view all the answers

In the complex [Ni(CO)4], what is the oxidation state of Ni?

0 Signup and view all the answers

Which of the following is an example of an anionic complex ion?

[Fe(CN)6]3- Signup and view all the answers

What characteristic allows transition metals to form complexes?

Small size and high effective nuclear charge Signup and view all the answers

What type of complex compound is formed when [Cu(NH3)4]SO4 is treated with excess AgNO3?

Cationic complex Signup and view all the answers

Why is CuSO4.5H2O blue while ZnSO4.7H2O is white?

The electronic transitions of d-electrons in CuSO4.5H2O cause its blue color. Signup and view all the answers

What property of transition metals allows them to act as catalysts?

Transition metals have vacant d-orbitals and can form unstable intermediates. Signup and view all the answers

Which equation demonstrates the catalytic role of Fe in the Haber process?

Fe + Mo: N2 + 3H2 -> 2NH3 Signup and view all the answers

Which conclusion can be drawn regarding the magnetic properties of transition elements?

Paramagnetic behavior arises from unpaired d-electrons in the metal. Signup and view all the answers

Which ion is more likely to be paramagnetic: Fe2+ or Fe3+?

Fe2+ has more unpaired electrons than Fe3+. Signup and view all the answers

What causes the color of transition metal compounds?

d-d transitions of unpaired electrons Signup and view all the answers

Which of the following ions is known to have a blue solution due to d-d transition?

Cu2+ Signup and view all the answers

Why are ions with completely filled d-orbitals colorless?

There is no d-d transition possible. Signup and view all the answers

What is the complementary color observed when orange light is absorbed?

Blue Signup and view all the answers

What phenomenon causes the purple color in KMnO4?

Charge transfer between Mn and O atoms Signup and view all the answers

What determines the color of transition metal compounds besides the nature of the metal ion?

The type of ligands and complex formed Signup and view all the answers

Which of the following states the electronic configuration of Cu2+ ion?

[Ar] 3d9 Signup and view all the answers

Why is anhydrous CuSO4 colorless compared to CuSO4.5H2O?

It lacks hydrated ions for d-d transition. Signup and view all the answers

What is the role of the central metal atom in a complex?

It is attached to ligands through coordinate bonds. Signup and view all the answers

Which of the following is an example of a bidentate ligand?

Oxalate ion (ox) Signup and view all the answers

In the complex [Co(en)3]Cl3, what is the coordination number of Co?

6 Signup and view all the answers

What defines a monodentate ligand?

It donates a pair of electrons through one atom. Signup and view all the answers

What is the term for the energy difference between the two sets of d-orbitals in an octahedral field?

Crystal field splitting energy Signup and view all the answers

In an octahedral complex, which d-orbitals experience more repulsion as ligands approach?

dx2-y2 and dz2 Signup and view all the answers

Which of the following statements about the coordination sphere is true?

It includes the central metal atom and directly attached ligands. Signup and view all the answers

What happens when ∆o is greater than pairing energy (P)?

Electrons tend to pair in the t2g level Signup and view all the answers

Identify the correct definition of the ionization sphere.

It is the part of the complex that is directly ionizable. Signup and view all the answers

What is a donor atom in the context of coordination complexes?

The atom in the ligand donating an electron pair to the central metal. Signup and view all the answers

Which of the following ligands would be classified as strong field based on the spectrochemical series?

Ammonia (NH3) Signup and view all the answers

Which of the following statements about high spin and low spin complexes is correct?

High spin complexes result from ∆o < P. Signup and view all the answers

Which ligand is classified as a polydentate ligand?

Diethylene triamine (dien) Signup and view all the answers

What is the expected color property of most transition metal compounds?

They are typically colored in both solid and solution forms. Signup and view all the answers

What occurs to the d-orbitals when ligands approach the central metal atom in an octahedral complex?

The d-orbitals split into t2g and eg sets. Signup and view all the answers

Which d-orbitals are considered part of the t2g set in an octahedral complex?

dxz, dyz, and dxy Signup and view all the answers

Which statement correctly defines d-block elements?

They are located between s and p block elements in the periodic table. Signup and view all the answers

Identify the element in the 3d series with the electronic configuration [Ar]3d^6 4s^2.

Iron (Fe) Signup and view all the answers

What is the general electronic configuration of d-block elements?

(n-1)d^1-10 ns^1-2 Signup and view all the answers

Which of the following elements is NOT considered a transition element?

Zinc (Zn) Signup and view all the answers

What defines transition elements specifically?

Elements with incompletely filled d-subshell. Signup and view all the answers

How can you determine the group number of a d-block element?

By adding the number of (n-1)d electrons and ns electrons. Signup and view all the answers

Which of the following elements occupies the 5th period and the 4d series?

Yttrium (Y) Signup and view all the answers

Which element in the 3d series has an unusual electronic configuration due to stability?

Chromium (Cr) Signup and view all the answers

Study Notes

Transition Elements

Transition elements are characterized by the presence of partially filled d-orbitals in their atoms or ions in their ground states or in any of their oxidation states
D-block elements lie between s and p block elements in the periodic table
They extend from group 3 to 12 and from period 4 to 7
The elements in which the last electron enters into the d-subshell are called d-block elements
Some d-block elements are not transition elements (e.g., Zn, Cd, and Hg) as they have completely filled d orbitals in their ground state and in common oxidation states.
The 4th period is also called the first d-series
The 5th period is also called the second d-series
The 6th period is also called the third d-series
The 7th period is also called the fourth d-series

Electronic Configuration of 3d series

The general outer electronic configuration of the d-block elements is (n-1)d^1-10 ns^1-2, where n is the principal quantum number of the valence shell
Sc (21): [Ar] 3d¹4s²
Ti (22): [Ar] 3d²4s²
V (23): [Ar] 3d³4s² and so on
Cr(24) has [Ar] 3d⁵4s¹, unusual configuration due to extra stability of half-filled orbitals
Cu(29) has [Ar] 3d¹⁰4s¹, unusual configuration due to extra stability of completely filled orbitals
Zn (30): [Ar] 3d¹⁰4s²

Characteristics of Transition Elements

All transition elements are metals. They show regular metallic properties like high density, malleability, ductility, high electrical & thermal conductivity, metallic lustre, high melting and boiling points, alloy formation
They show variable valency and oxidation states in their compounds
They show a strong tendency to form complex compounds
Majority of transition elements and compounds exhibit paramagnetic behavior due to the presence of unpaired d-electrons
Many transition elements and compounds show coloured ions and compounds due to d–d transition
Most of the transition metals and their compounds show good catalytic properties in various chemical processes

Oxidation States of Transition Metals

Transition elements show variable oxidation states in their compounds due to the similar energies of ns and (n-1)d electrons
Typical oxidation state for most transition metals is +2
The number of oxidation states increases with increasing atomic number from Sc to Mn and then decreases to Zn

Complex Formation

Transition metals show a strong tendency to form complexes
Transition metals atoms or ions are small in size with high effective nuclear charge, capable of accepting lone pairs of electrons from electron-rich species (ions or molecules) called ligands
They have vacant d-orbitals with suitable energy levels to accommodate electron pairs donated by ligands

Complex Ions

An electrically charged species in which a metal atom or ion is coordinated to several electron-rich species (ions or molecules) is called a complex ion
Cationic complex ions have positive charge; e.g., [Cu(NH₃)₄]²⁺, [Ag(NH₃)₂]⁺
Anionic complex ions have negative charge; e.g., [Fe(CN)₆]³⁻, [CuCl₄]²⁻

Complex Compounds

Compounds containing at least one complex ion which retains its identity in solid and solution forms are called complex compounds
A complex ion remains intact in solution
A complex compound generally ionizes

Ligands

Electron-rich species (ions or molecules) that form coordinate bonds with a metal atom or ion in a complex are known as ligands or coordinating groups
Monodentate ligands have one donor atom (e.g., Cl^-, Br^-, OH^-, H₂O, NH₃, CO)
Bidentate ligands have two donor atoms (e.g., ethylene diamine (en), oxalate ion (ox))
Polydentate ligands have multiple donor atoms (e.g., diethylenetriamine (dien), ethylene diamine tetraacetic acid (EDTA))

Coordination Number

The total number of ligands (and their donor atoms) directly attached to the central metal atom or ion is called the coordination number
Common coordination numbers are 2, 4, 6

Coordination Sphere and Ionization Sphere

The central metal along with the directly attached ligands make up the coordination sphere, which is non-ionizable
The region outside the coordination sphere is the ionization sphere, which is ionizable

Effective Atomic Number (EAN)

The total number of electrons in a complex ion, including those of the central metal and those gained from ligands is known as EAN
In many instances, the EAN matches the atomic number of the next noble gas

Shapes of Complex Ions

Geometry of complex ions can be predicted by the coordination number of the central metal ion or atom
Coordination number 2 leads to linear geometry
Coordination number 4 gives tetrahedral or square planar geometry
Coordination number 6 leads to octahedral geometry

Magnetic Properties

Most transition metal compounds exhibit paramagnetism due to the presence of unpaired d-electrons
The magnetic moment (μ) is calculated using the formula μ = √n(n+2) BM, where n is the number of unpaired electrons and BM is the Bohr magneton
Sc³⁺, Ti⁴⁺, Cu⁺ have no unpaired electrons and are diamagnetic

Colour of Transition Metal Compounds

Many transition metal compounds are colored in solution and solid state
Colour arises from d-d transitions of electrons between d-energy levels within the complex ion
Ligands affect the energy difference between d-orbitals, consequently affecting colour

Catalytic Properties of Transition Metals

Many transition metals and their compounds act as catalysts due to the presence of vacant d-orbitals and variable oxidation states, facilitating formation of unstable intermediates
Fine division of transition metals increases surface area, accelerating the reaction rate through adsorption of reactant molecules

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