What is the electronic configuration of $\text{Cr}^{3+}$?

Correct Option: A. Solution: The electronic configuration of $\text{Cr}^{3+}$ is [Ar] 3d\^3.

What is the electronic configuration of $ ext{Mn}^{2+}$?

Correct Option: A. Solution: The electronic configuration of $ ext{Mn}^{2+}$ is [Ar] 3d^5.

The d- and f-Block Elements

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Summary

The d- and f-block elements include transition metals and inner transition metals.
Transition metals (d-block) have partially filled d orbitals, while inner transition metals (f-block) have partially filled f orbitals.
The d-block consists of elements in groups 3-12, while the f-block includes lanthanoids and actinoids.
Key characteristics of transition metals:
- Exhibit variable oxidation states.
- Form colored compounds.
- Act as catalysts in various reactions.
The stability of oxidation states can be analyzed using standard electrode potential values.
The chemistry of lanthanoids is simpler compared to actinoids due to fewer oxidation states and less radioactivity.
Potassium permanganate (KMnO₄) is a strong oxidizing agent used in organic chemistry and analytical applications.
Common reactions involving KMnO₄ include:
- Oxidation of oxalate ions to carbon dioxide.
- Oxidation of hydrogen sulfide to sulfur.
- Oxidation of sulfite to sulfate.
The preparation of potassium dichromate (K₂Cr₂O₇) involves chromite ore, while KMnO₄ is prepared from pyrolusite ore.

Learning Objectives

Understand the positions of the d- and f-block elements in the periodic table.
Learn the electronic configurations of transition (d-block) and inner transition (f-block) elements.
Appreciate the relative stability of various oxidation states in terms of electrode potential values.
Describe the preparation, properties, structures, and uses of important compounds such as K₂Cr₂O₇ and KMnO₄.
Understand the general characteristics of the d- and f-block elements and the trends in their properties.

Detailed Notes

Notes on d- and f- Block Elements

1. Introduction to Transition Elements

The d-block consists of groups 3-12 in the periodic table.
Transition metals have partially filled d orbitals.
Common transition metals include iron, copper, silver, and gold.

2. Electronic Configurations

General electronic configuration: (n-1)d¹⁰ns¹⁻².
Exceptions:
- Chromium (Cr): 3d⁵ 4s¹ instead of 3d⁴ 4s².
- Copper (Cu): 3d¹⁰ 4s¹ instead of 3d⁹ 4s².

3. Oxidation States

Transition metals exhibit multiple oxidation states due to the involvement of d electrons.
Common oxidation states include +2, +3, and higher.

4. Properties of Transition Metals

Paramagnetism: Many transition metals and their compounds show paramagnetic behavior due to unpaired electrons.
Catalytic Activity: Transition metals often act as catalysts in various chemical reactions.
Color: Transition metal compounds are typically colored due to d-d electron transitions.

5. Inner Transition Elements

Comprises lanthanoids and actinoids.
Lanthanoids: Elements following lanthanum (atomic numbers 57-71).
Actinoids: Elements following actinium (atomic numbers 89-103).
Actinoids exhibit a wider range of oxidation states and are often radioactive.

6. Preparation of Compounds

Potassium Dichromate (K₂Cr₂O₇): Prepared from chromite ore.
Potassium Permanganate (KMnO₄): Prepared from pyrolusite ore.

7. Reactions Involving Potassium Permanganate

Oxidation reactions in acidic solutions:
- Oxalic acid: 5C₂O₄²⁻ + 2MnO₄ + 16H⁺ → 2Mn²⁺ + 8H₂O + 10CO₂
- Hydrogen sulfide: H₂S + 2MnO₄ + 16H⁺ → 2Mn²⁺ + 8H₂O + 5S

8. Disproportionation Reactions

Definition: A reaction where a substance is simultaneously oxidized and reduced.
Example: Cu⁺ undergoes disproportionation to form Cu²⁺ and Cu.

9. Stability of Oxidation States

Mn²⁺ compounds are more stable than Fe²⁺ towards oxidation to their +3 state due to electronic configuration stability.

10. Characteristics of Lanthanoids vs. Actinoids

Lanthanoids: Generally exhibit +3 oxidation state, less complex chemistry.
Actinoids: Exhibit multiple oxidation states, more complex due to radioactivity.

11. Summary of Key Points

Transition metals are defined by their d orbital configurations and exhibit unique properties.
Inner transition metals have distinct characteristics and complexities in their chemistry.

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Misunderstanding Oxidation States: Students often confuse the oxidation states of transition metals, especially in complex reactions. Ensure to memorize the common oxidation states for each metal.
Ignoring Electronic Configurations: Failing to write or understand the electronic configurations can lead to incorrect predictions about stability and reactivity. Always double-check configurations for ions.
Overlooking Reaction Conditions: Many reactions depend on specific conditions (e.g., pH, temperature). Be aware of how these conditions affect the outcomes.

Tips for Success

Practice Ionic Equations: Write out ionic equations for common reactions involving transition metals, such as those with permanganate ions. This will help reinforce your understanding of redox processes.
Utilize E° Values: Familiarize yourself with standard electrode potentials (E° values) for transition metals. This knowledge is crucial for predicting the feasibility of redox reactions.
Study Color Properties: Transition metals often exhibit characteristic colors in solution. Learn to predict which ions will be colored and why, as this is a common exam question.
Understand Disproportionation: Be clear on what disproportionation means and be able to provide examples, as this concept frequently appears in exam questions.
Compare and Contrast: When asked to compare the chemistry of lanthanoids and actinoids, focus on differences in oxidation states, electronic configurations, and reactivity. Use tables for clarity.
Review Common Reactions: Familiarize yourself with common reactions of transition metals, such as oxidation with permanganate, to ensure you can write the correct ionic equations under exam conditions.

Practice & Assessment

Multiple Choice Questions

They have variable oxidation states.

They do not form colored compounds.

They are not good catalysts.

They have low melting points.

Correct Answer: A

Solution:

Transition metals have variable oxidation states, which is a characteristic feature of these elements.

Due to the presence of unpaired s electrons.

Due to the presence of unpaired d electrons.

Due to the presence of paired p electrons.

Due to the absence of unpaired electrons.

Correct Answer: B

Solution:

Transition metals often exhibit paramagnetic behavior due to the presence of unpaired d electrons, which contribute to their magnetic properties.

Manganese

Iron

Copper

Zinc

Correct Answer: A

Solution:

Manganese exhibits all oxidation states from +2 to +7, which is the highest range among transition metals.

Copper (Cu)

Zinc (Zn)

Nickel (Ni)

Cobalt (Co)

Correct Answer: B

Solution:

Zinc (Zn) has a completely filled d subshell (3d¹⁰) in its ground state and common oxidation state (+2), hence it does not exhibit variable oxidation states and is not considered a transition metal.

Iron

Copper

Gold

Silver

Correct Answer: A

Solution:

Iron is known to form interstitial compounds due to its ability to trap small atoms like hydrogen, carbon, or nitrogen in its crystal lattice.

Titanium (Ti)

Copper (Cu)

Zinc (Zn)

Silver (Ag)

Correct Answer: A

Solution:

Titanium (Ti) is known to form interstitial compounds such as TiN, which are extremely hard and have high melting points. This is due to the small nitrogen atoms being trapped in the metal lattice.

Due to the high third ionization energy required to achieve the +3 state.

Because Mn³⁺ is a strong reducing agent.

Because Mn³⁺ has a completely filled d subshell.

Due to the low enthalpy of atomization of Mn.

Correct Answer: A

Solution:

The +3 oxidation state of manganese is of little importance because the transition from d⁵ to d⁴ configuration requires a much larger third ionization energy. This makes the +3 state less stable compared to the +2 and +7 states.

Addition of sulfuric acid

Fusion with sodium carbonate

Roasting with oxygen

Reduction with carbon

Correct Answer: C

Solution:

Roasting with oxygen is crucial for the oxidation of Cr³⁺ to Cr⁶⁺, forming CrO₄²⁻ ions, which are then converted to dichromate ions.

Iron

Nickel

Copper

Zinc

Correct Answer: B

Solution:

Nickel has a density of 8.9 g/cm

^3

, which is the highest among the first series of transition elements.

High melting points

Low density

Non-conductivity

Lack of color in compounds

Correct Answer: A

Solution:

Transition metals are known for their high melting points and other metallic properties.

It causes a decrease in atomic radii.

It increases the reactivity of elements.

It leads to higher oxidation states.

It results in lower melting points.

Correct Answer: A

Solution:

Lanthanoid contraction causes a decrease in atomic radii, affecting the elements following the lanthanoids.

They have completely filled d orbitals.

Their d orbitals are involved in bonding, allowing different numbers of electrons to be used.

Their s orbitals are always filled, preventing oxidation.

They have no d electrons available for bonding.

Correct Answer: B

Solution:

Transition metals exhibit variable oxidation states because their d orbitals are involved in bonding, allowing them to use different numbers of electrons for bonding.

Iron

Copper

Nickel

Zinc

Correct Answer: C

Solution:

Nickel has the highest density among the given options, with a density of 8.9 g/cm³.

Manganese

Iron

Chromium

Copper

Correct Answer: C

Solution:

Chromium has one of the highest enthalpies of atomisation due to its strong metallic bonding and the presence of unpaired d electrons.

Titanium

Copper

Silver

Gold

Correct Answer: A

Solution:

Titanium is known for forming interstitial compounds, such as TiC, where small atoms like carbon are trapped within its crystal lattice.

Manganese

Iron

Nickel

Copper

Correct Answer: A

Solution:

Manganese has a half-filled d⁵ configuration in Mn²⁺, which contributes to its more positive E° value compared to the general trend.

Vanadium (V)

Iron (Fe)

Nickel (Ni)

Copper (Cu)

Correct Answer: B

Solution:

Iron is used as a catalyst in the Haber process for ammonia synthesis. Its ability to adopt multiple oxidation states and form complexes makes it effective in catalyzing reactions.

Vanadium (V)

Nickel (Ni)

Iron (Fe)

Platinum (Pt)

Correct Answer: C

Solution:

Iron (Fe) is used as a catalyst in the Haber process due to its ability to adopt multiple oxidation states and form complexes, which facilitates the conversion of nitrogen and hydrogen into ammonia.

Transition metals are poor catalysts due to their inability to change oxidation states.

Transition metals are effective catalysts because they can form complexes and adopt multiple oxidation states.

Transition metals are effective catalysts only in gaseous reactions.

All transition metals act as catalysts in the same manner.

Correct Answer: B

Solution:

Transition metals are known for their catalytic activity because they can adopt multiple oxidation states and form complexes, which facilitates reactions.

Scandium (Sc)

Iron (Fe)

Manganese (Mn)

Chromium (Cr)

Correct Answer: B

Solution:

Iron (Fe) forms a stable +3 oxidation state due to its half-filled d subshell (3d⁵) after losing three electrons, which provides extra stability.

Vanadium (V)

Zinc (Zn)

Silver (Ag)

Mercury (Hg)

Correct Answer: A

Solution:

Vanadium (V) is a good catalyst because it can adopt multiple oxidation states, which allows it to facilitate various chemical reactions by providing different pathways. This is a common property of transition metals, unlike elements like Zinc, Silver, and Mercury, which have more limited oxidation states.

Iron

Copper

Zinc

Silver

Correct Answer: A

Solution:

Iron is used as a catalyst in the Haber process for the synthesis of ammonia.

Scandium

Chromium

Iron

Copper

Correct Answer: B

Solution:

Chromium has the highest enthalpy of atomisation among the given options, which is indicative of strong metallic bonding.

The solution becomes more acidic.

The solution becomes more basic.

The solution remains neutral.

The solution decomposes.

Correct Answer: B

Solution:

Increasing the pH of a potassium dichromate solution makes it more basic, as dichromate ions are converted to chromate ions.

Manganese (Mn)

Chromium (Cr)

Iron (Fe)

Nickel (Ni)

Correct Answer: B

Solution:

Chromium (Cr) has the electronic configuration of 3d⁵ 4s¹ in its ground state. This configuration is due to the stability provided by the half-filled d subshell.

They have high melting points.

They can adopt multiple oxidation states.

They are non-reactive.

They are abundant.

Correct Answer: B

Solution:

Transition metals are often used as catalysts because they can adopt multiple oxidation states, which allows them to facilitate various chemical reactions.

Titanium

Copper

Zinc

Silver

Correct Answer: A

Solution:

Titanium is known to form interstitial compounds such as TiC and TiH₁.₇, where small atoms like carbon and hydrogen are trapped in the metal lattice.

Scandium (Sc)

Manganese (Mn)

Copper (Cu)

Zinc (Zn)

Correct Answer: B

Solution:

Manganese exhibits oxidation states from +2 to +7, which is the largest range among the transition metals. This is due to the presence of five d electrons that can be involved in bonding.

Poor shielding of 4f electrons

High atomic mass

Increase in nuclear charge

Presence of d electrons

Correct Answer: A

Solution:

The lanthanoid contraction is primarily due to the poor shielding effect of 4f electrons, which leads to a decrease in atomic and ionic radii across the lanthanoid series.

Nickel

Iron

Copper

Zinc

Correct Answer: A

Solution:

Nickel is commonly used as a catalyst in the catalytic hydrogenation process.

[Ar] 3d¹⁰ 4s¹

[Ar] 3d¹⁰

[Ar] 3d⁹ 4s²

[Ar] 3d⁹ 4s¹

Correct Answer: B

Solution:

The electronic configuration of Cu⁺ is [Ar] 3d¹⁰, as it loses one electron from the 4s orbital.

Copper

Zinc

Nickel

Iron

Correct Answer: B

Solution:

Zinc has a completely filled d subshell in its ground state with the electronic configuration [Ar] 3d^10 4s^2.

Scandium

Zinc

Copper

Iron

Correct Answer: B

Solution:

Zinc has a completely filled 3d¹⁰ subshell in its ground state, which makes it less reactive and limits it to the +2 oxidation state.

Scandium

Zinc

Nickel

Copper

Correct Answer: B

Solution:

Zinc is not considered a transition metal because it has a completely filled d orbital (3d¹⁰) in its ground state as well as in its common oxidation state.

Iron

Vanadium

Nickel

Copper

Correct Answer: B

Solution:

Vanadium(V) oxide is commonly used as a catalyst in the Contact Process for the production of sulfuric acid.

Zinc

Copper

Iron

Scandium

Correct Answer: C

Solution:

Iron is known for its catalytic properties, particularly in processes like the Haber process, due to its ability to form complexes and multiple oxidation states.

Copper

Chromium

Zinc

Silver

Correct Answer: B

Solution:

Chromium is used in the production of stainless steel due to its ability to form hard alloys.

[Ar] 3d^3

[Ar] 3d^4

[Ar] 3d^5

[Ar] 3d^6

Correct Answer: A

Solution:

The electronic configuration of

\text{Cr}^{3+}

is [Ar] 3d^3.

High melting points

Formation of coloured compounds

Low density

Inertness to acids

Correct Answer: B

Solution:

Transition metals form coloured compounds due to d-d electronic transitions within their partially filled d orbitals.

Mn²⁺ has a half-filled d subshell, which is more stable.

Fe²⁺ has a completely filled d subshell.

Mn²⁺ has a higher atomic number.

Fe²⁺ is more electropositive.

Correct Answer: A

Solution:

Mn²⁺ has a half-filled d⁵ subshell, which is particularly stable, making it less likely to oxidize to Mn³⁺.

Transition metals have partially filled d orbitals that allow for variable electron configurations.

Transition metals have completely filled d orbitals, which stabilize multiple oxidation states.

Transition metals have no d orbitals, allowing them to exhibit multiple oxidation states.

Transition metals have a single oxidation state due to their filled s orbitals.

Correct Answer: A

Solution:

Transition metals have partially filled d orbitals, allowing them to lose different numbers of electrons and exhibit multiple oxidation states.

[Ar] 3d^5

[Ar] 3d^4

[Ar] 3d^6

[Ar] 3d^3

Correct Answer: A

Solution:

The electronic configuration of

ext{Mn}^{2+}

is [Ar] 3d^5.

Iron

Copper

Nickel

Chromium

Correct Answer: D

Solution:

Chromium has a high enthalpy of atomization, which contributes to its high melting point and strength, making it useful in steel alloys.

They are all non-radioactive.

They exhibit a wide range of oxidation states.

They are unaffected by acids.

They have no magnetic properties.

Correct Answer: B

Solution:

Actinoids exhibit a wide range of oxidation states and many of them are radioactive, making their chemistry complex.

Due to the low ionisation energy of Mn.

Due to the high ionisation energy of Mn.

Due to the stability of the d

^5

configuration in Mn²⁺.

Due to the instability of the d

^5

configuration in Mn²⁺.

Correct Answer: C

Solution:

The E° value for the Mn/Mn²⁺ couple is more positive due to the stability of the half-filled d

^5

configuration in Mn²⁺.

They have low melting points.

They are chemically reactive.

They are poor conductors of electricity.

They are very hard and have high melting points.

Correct Answer: D

Solution:

Interstitial compounds, like those formed by transition metals, are known for their high melting points and hardness, often exceeding that of the pure metals.

Iron

Copper

Zinc

Silver

Correct Answer: A

Solution:

Iron is used as a catalyst in the Haber process due to its ability to adopt multiple oxidation states and form complexes, which facilitates the reaction.

Manganese

Nickel

Copper

Zinc

Correct Answer: B

Solution:

Nickel in its +2 oxidation state has a high enthalpy of hydration, making it a strong reducing agent compared to other transition metals.

They have high melting points.

They are highly reactive.

They are soluble in water.

They are poor conductors of electricity.

Correct Answer: A

Solution:

Interstitial compounds have high melting points, which is one of their characteristic properties.

Increased reactivity with non-metals

Similar radii of second and third d series elements

Higher oxidation states in early transition metals

Decreased density of transition metals

Correct Answer: B

Solution:

The lanthanoid contraction results in the second and third d series elements having similar radii, which affects their chemical and physical properties.

Vanadium

Nickel

Iron

Copper

Correct Answer: C

Solution:

Finely divided iron is used as a catalyst in the Haber process due to its ability to adopt multiple oxidation states and form complexes.

Scandium

Manganese

Copper

Zinc

Correct Answer: B

Solution:

Manganese exhibits oxidation states from +2 to +7, the highest range among transition metals.

High density

Ability to form interstitial compounds

Variable oxidation states

High melting points

Correct Answer: C

Solution:

Transition metals can act as good catalysts due to their ability to change oxidation states, which facilitates the formation and breaking of bonds during chemical reactions.

Scandium (Sc)

Zinc (Zn)

Copper (Cu)

Calcium (Ca)

Correct Answer: C

Solution:

Copper (Cu) forms colored compounds due to the presence of partially filled d orbitals, which allow for d-d transitions that absorb visible light.

Irregular variation of ionization enthalpies and sublimation enthalpies.

Consistent increase in atomic radius across the series.

Constant enthalpy of hydration across the series.

Regular variation in the density of the elements.

Correct Answer: A

Solution:

The irregularity in the E° values across the first row transition metals can be explained by the irregular variation of ionization enthalpies (sum of the first and second ionization enthalpies) and sublimation enthalpies, which affect the stability of the metal ions in solution.

Nickel

Iron

Copper

Zinc

Correct Answer: A

Solution:

Nickel can form complexes like Ni(CO)₄ where the carbonyl ligand acts as a π-acceptor, stabilizing the metal in a low oxidation state (zero).

Increased reactivity of actinoids compared to lanthanoids.

Similar radii and properties of elements in the second and third transition series.

Decreased density of transition elements.

Increased metallic character of transition elements.

Correct Answer: B

Solution:

The lanthanoid contraction leads to similar radii and properties of elements in the second and third transition series, such as Zr and Hf.

Titanium

Copper

Zinc

Silver

Correct Answer: A

Solution:

Titanium is known for forming interstitial compounds such as TiC (titanium carbide) and TiH (titanium hydride), which are characterized by high hardness and melting points.

Manganese

Iron

Copper

Zinc

Correct Answer: A

Solution:

Manganese is known for exhibiting the oxidation state +7.

The decrease in atomic and ionic sizes of lanthanoids with increasing atomic number.

The increase in atomic size across the lanthanoid series.

The expansion of d-orbitals in transition metals.

The increase in density of lanthanoids with decreasing atomic number.

Correct Answer: A

Solution:

Lanthanoid contraction refers to the decrease in atomic and ionic sizes of lanthanoids as the atomic number increases, due to poor shielding by 4f electrons.

Scandium

Titanium

Manganese

Copper

Correct Answer: C

Solution:

Manganese exhibits oxidation states from +2 to +7, making it known for its wide range of oxidation states.

Mn²⁺ has a half-filled d subshell

Fe²⁺ has a completely filled d subshell

Mn²⁺ has a completely filled d subshell

Fe²⁺ has a half-filled d subshell

Correct Answer: A

Solution:

Mn²⁺ has a half-filled d subshell (3d⁵), which is more stable and less likely to oxidize to Mn³⁺ compared to Fe²⁺.

Due to the presence of unpaired electrons

Because of their large atomic size

Due to their high melting points

Because they are good conductors of electricity

Correct Answer: A

Solution:

Transition metals form colored compounds due to the presence of unpaired d electrons, which can absorb visible light and undergo d-d transitions.

Titanium

Vanadium

Chromium

Manganese

Correct Answer: A

Solution:

Titanium can exhibit a +4 oxidation state and is used in the pigment industry in the form of titanium dioxide (TiO₂).

[Ar] 3d^3

[Ar] 3d^5

[Ar] 3d^4

[Ar] 3d^6

Correct Answer: A

Solution:

The electronic configuration of

\text{Cr}^{3+}

is [Ar] 3d^3, as it loses three electrons from its 4s and 3d orbitals.

Increased nuclear charge with poor shielding by 4f electrons.

Decrease in atomic mass across the series.

Effective shielding by 4f electrons.

Decrease in the number of 4f electrons.

Correct Answer: A

Solution:

The lanthanoid contraction is primarily due to the increased nuclear charge with poor shielding by the 4f electrons, leading to a decrease in atomic and ionic radii across the series.

Scandium

Titanium

Zinc

Vanadium

Correct Answer: C

Solution:

Zinc is not considered a transition element because it has a completely filled d subshell (3d¹⁰) in its ground state and common oxidation states.

Scandium

Zinc

Iron

Copper

Correct Answer: B

Solution:

Zinc is not considered a transition metal because it has a completely filled d orbital in its ground state.

[Ar] 3d³

[Ar] 3d⁵

[Ar] 3d⁴

[Ar] 3d²

Correct Answer: A

Solution:

The electronic configuration of Cr³⁺ is [Ar] 3d³, as it loses three electrons from its 3d and 4s orbitals.

Copper

Zinc

Iron

Nickel

Correct Answer: B

Solution:

Zinc is not considered a transition metal because it has completely filled d orbitals (3d¹⁰) in its ground state.

[Ar] 3d

^9

^2

[Ar] 3d

^9

^1

[Ar] 3d

^10

[Ar] 3d

^10

^0

Correct Answer: C

Solution:

In the +1 oxidation state, copper loses one electron from the 4s orbital, resulting in the configuration [Ar] 3d

^10

True or False

Correct Answer: True

Solution:

The variability of oxidation states in transition elements arises from the incomplete filling of d orbitals, allowing for oxidation states that differ by unity.

Correct Answer: False

Solution:

Transition metals vary widely in their chemical reactivity, and some are 'noble' and unaffected by single acids, unlike many non-transition metals.

Correct Answer: True

Solution:

The actinoids can exist in multiple oxidation states, making their chemistry more complex compared to lanthanoids.

Correct Answer: True

Solution:

Transition elements exhibit variability in oxidation states because of their incomplete d orbitals, allowing for different numbers of electrons to be lost or shared.

Correct Answer: False

Solution:

Transition elements have incompletely filled d orbitals in their ground state, which is a characteristic feature distinguishing them from non-transition elements.

Correct Answer: True

Solution:

The maximum oxidation states of reasonable stability for transition elements correspond to the sum of the s and d electrons up to manganese.

Correct Answer: False

Solution:

While some transition metals are noble and unaffected by single acids, many are electropositive enough to dissolve in mineral acids.

Correct Answer: True

Solution:

The E° values for Mn, Ni, and Zn deviate from the expected trend due to factors like ionisation enthalpies and hydration enthalpies.

Correct Answer: True

Solution:

The actinoids are highly reactive metals, particularly when finely divided, as they react with boiling water and most non-metals at moderate temperatures.

Correct Answer: True

Solution:

Transition metals form many complex compounds because of their small ionic sizes, high ionic charges, and availability of d orbitals for bonding.

Correct Answer: False

Solution:

The lanthanoid contraction affects the properties of elements succeeding the lanthanoids, not the actinoids.

Correct Answer: True

Solution:

The magnetic properties of the actinoids are more complex due to the variation in the magnetic susceptibility with the number of unpaired 5f electrons, which is more intricate than the corresponding results for the lanthanoids.

Correct Answer: True

Solution:

The formation of complex compounds by transition metals is attributed to their comparatively smaller sizes, high ionic charges, and the availability of d orbitals for bond formation.

Correct Answer: True

Solution:

The variability in oxidation states of transition metals arises from the incomplete filling of d orbitals, allowing oxidation states to differ by unity.

Correct Answer: True

Solution:

The actinoids are highly reactive metals, especially when finely divided, and they react with boiling water and most non-metals at moderate temperatures.

Correct Answer: False

Solution:

Transition metals vary widely in their chemical reactivity, and some are 'noble' and unaffected by single acids, unlike many non-transition metals.

Correct Answer: True

Solution:

Transition metals exhibit catalytic properties because they can adopt multiple oxidation states and form complexes, which aids in catalytic processes.

Correct Answer: True

Solution:

Transition elements exhibit variable oxidation states because of the incomplete filling of their d orbitals.

Correct Answer: True

Solution:

The electronic configuration of outer orbitals of transition elements is generally (n-1)d 10ns¹⁻², except for some exceptions like Pd.

Correct Answer: True

Solution:

Manganese is known for exhibiting all oxidation states from +2 to +7, which is a characteristic of transition metals.

Correct Answer: True

Solution:

Transition metals can change oxidation states, which makes them effective catalysts, as seen in processes like the Haber and Contact processes.

Correct Answer: True

Solution:

Transition metals form interstitial compounds by trapping small atoms within their crystal lattices, leading to properties like high melting points and hardness.

Correct Answer: True

Solution:

Actinoids can exist in multiple oxidation states, which adds complexity to their chemistry.

Correct Answer: True

Solution:

Transition metals form interstitial compounds when small atoms like H, C, or N are trapped inside the crystal lattices of metals.

Correct Answer: True

Solution:

The general electronic configuration for transition elements is (n-1)d

^{10}

^{1-2}

, but exceptions exist due to energy differences between orbitals.

Correct Answer: True

Solution:

Transition metals and their compounds exhibit catalytic activity because they can form complexes and change oxidation states, which facilitates reactions.

Correct Answer: True

Solution:

Transition metals and their compounds exhibit catalytic properties due to their ability to adopt multiple oxidation states and form complexes.

Correct Answer: True

Solution:

The actinoids are highly reactive, especially when finely divided, and can react with non-metals at moderate temperatures, unlike lanthanoids.

Correct Answer: False

Solution:

The electronic configuration of copper is actually 3d

^{10}

^1

, not 3d

^9

^2

. This is due to the stability associated with a completely filled d subshell.

Correct Answer: True

Solution:

Pd has an electronic configuration of 4d^{10}5s^{0}, which deviates from the typical (n-1)d^{10}ns^{1-2} configuration.

Correct Answer: True

Solution:

The actinoids are indeed highly reactive, particularly when finely divided, as they react with boiling water and combine with most non-metals at moderate temperatures.

Correct Answer: True

Solution:

The general electronic configuration for transition elements is (n-1)d

^{1-10}

^{1-2}

, with exceptions due to small energy differences between d and s orbitals.

Correct Answer: False

Solution:

Zinc is not considered a transition element because it has a completely filled 3d orbital in its ground state.

Correct Answer: False

Solution:

Transition elements have incompletely filled d orbitals in their common oxidation states, which is a characteristic feature of these elements.

Correct Answer: True

Solution:

The lanthanoid contraction causes elements in the second and third d series to have similar radii, such as Zr and Hf.

Correct Answer: True

Solution:

Transition metals have high enthalpies of atomisation because of their strong metallic bonding, which is a result of the overlap of d orbitals.

Correct Answer: True

Solution:

Palladium has an electronic configuration of 4d¹⁰5s⁰, which is an exception to the general configuration of d-block elements.

Correct Answer: False

Solution:

The transition metals form a large number of complex compounds due to their smaller sizes, high ionic charges, and the availability of d orbitals for bond formation.

Correct Answer: False

Solution:

Scandium is considered a transition element because it has an incompletely filled 3d orbital in its ground state.

Correct Answer: True

Solution:

The lanthanoid contraction occurs due to the imperfect shielding of 4f electrons, leading to a decrease in atomic and ionic radii across the series.

Correct Answer: False

Solution:

The actinoid contraction is greater from element to element than the lanthanoid contraction.

Correct Answer: True

Solution:

The actinoids are highly reactive metals, especially when finely divided, as they react with boiling water and most non-metals at moderate temperatures.

Correct Answer: True

Solution:

The lanthanoid contraction causes the second and third d series elements to have similar radii, leading to similar physical and chemical properties.

Correct Answer: True

Solution:

Scandium has an incompletely filled 3d orbital in its ground state, which qualifies it as a transition element.

Correct Answer: True

Solution:

The small energy difference between (n-1)d and ns orbitals allows for exceptions in electronic configurations, as seen in elements like Cr and Cu.

Correct Answer: False

Solution:

The chemistry of actinoids is more complex due to their ability to exist in different oxidation states and their radioactive nature.

Correct Answer: True

Solution:

The lanthanoid contraction has more significant effects on the properties of succeeding elements compared to the actinoid contraction.

Correct Answer: False

Solution:

Zinc is not considered a transition element because it has a completely filled d orbital (3d¹⁰) in its ground state.

Correct Answer: False

Solution:

The ionisation enthalpies of the early actinoids are lower than those of the early lanthanoids due to less effective shielding of 5f electrons.

Correct Answer: True

Solution:

The variability in oxidation states of transition metals arises from the incomplete filling of d orbitals, allowing for oxidation states that differ by unity.

Correct Answer: True

Solution:

Transition metals form coloured compounds because of the d-d electron transitions that occur in their partially filled d orbitals.

Correct Answer: True

Solution:

The lanthanoid contraction leads to a decrease in atomic size, resulting in similar radii for the second and third d series.

Correct Answer: False

Solution:

Transition metals generally form colored compounds due to the d-d electron transitions.

Correct Answer: True

Solution:

The d-block elements occupy the large middle section of the periodic table, flanked between the s-block and p-block.

Correct Answer: True

Solution:

The lanthanoid contraction causes the second and third d series to have similar radii and thus similar physical and chemical properties.

Correct Answer: True

Solution:

The lanthanoid contraction results in similar radii and properties for elements like Zr and Hf, which have similar radii despite being in different series.

Correct Answer: False

Solution:

While some transition metals are 'noble' and unaffected by single acids, many are electropositive enough to dissolve in mineral acids.

Correct Answer: True

Solution:

Transition metals form coloured compounds because the d electrons can absorb visible light, which promotes them to higher energy levels. This absorption of light is responsible for the colours observed.

Correct Answer: True

Solution:

The general electronic configuration of transition elements is (n-1)d

^{10}

^{1-2}

, but palladium is an exception with its configuration being 4d

^{10}

^{0}

Correct Answer: False

Solution:

Transition metals have high enthalpies of atomisation due to strong metallic bonding.

Correct Answer: False

Solution:

Scandium is considered a transition element because it has an incompletely filled 3d orbital (3d

^{1}

) in its ground state.

Correct Answer: True

Solution:

Transition metals form complex compounds because of their comparatively smaller sizes, high ionic charges, and the availability of d orbitals for bond formation.

The d- and f-Block Elements

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Summary

Learning Objectives

Detailed Notes

Notes on d- and f- Block Elements

1. Introduction to Transition Elements

2. Electronic Configurations

3. Oxidation States

4. Properties of Transition Metals

5. Inner Transition Elements

6. Preparation of Compounds

7. Reactions Involving Potassium Permanganate

8. Disproportionation Reactions

9. Stability of Oxidation States

10. Characteristics of Lanthanoids vs. Actinoids

11. Summary of Key Points

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Tips for Success

Practice & Assessment

Multiple Choice Questions

Q1.Which of the following statements about transition metals is true?

Correct Answer: A

Q2.Why do transition metals often exhibit paramagnetic behavior?

Correct Answer: B

Q3.Which of the following transition metals is known to exhibit the highest number of oxidation states?

Correct Answer: A

Q4.Which of the following elements does not exhibit variable oxidation states and is not considered a transition metal?

Correct Answer: B

Q5.Which of the following metals is known to form interstitial compounds?

Correct Answer: A

Q6.Which of the following transition metals is most likely to form an interstitial compound with nitrogen, resulting in a very hard material?

Correct Answer: A

Q7.Why is the +3 oxidation state of manganese (Mn) of little importance compared to its +2 and +7 states?

Correct Answer: A

Q8.In the preparation of potassium dichromate from iron chromite ore, which of the following steps is crucial for the oxidation of Cr³⁺ to Cr⁶⁺?

Correct Answer: C

Q9.Which transition metal has the highest density among the first series of transition elements?

Correct Answer: B

Q10.Which of the following is a characteristic property of transition metals?

Correct Answer: A

Q11.What is the effect of lanthanoid contraction on the elements following the lanthanoids in the periodic table?

Correct Answer: A

Q12.Which of the following statements best explains why transition metals often exhibit variable oxidation states?

Correct Answer: B

Q13.Which of the following transition metals has the highest density?

Correct Answer: C

Q14.Which of the following transition metals is known to have the highest enthalpy of atomisation?

Correct Answer: C

Q15.Which of the following transition metals is known for its ability to form interstitial compounds?

Correct Answer: A

Q16.Which of the following transition metals has a more positive standard electrode potential (E°) for the M²⁺/M couple compared to the general trend, due to its stable half-filled d subshell?

Correct Answer: A

Q17.Which of the following transition metals is known for its catalytic activity in the Haber process due to its ability to adopt multiple oxidation states?

Correct Answer: B

Q18.Which transition metal is used as a catalyst in the Haber process for ammonia synthesis?

Correct Answer: C

Q19.Which of the following statements about the catalytic properties of transition metals is true?

Correct Answer: B

Q20.Which of the following transition metals is known to form the most stable +3 oxidation state due to its electronic configuration?

Correct Answer: B

Q21.Which of the following transition metals is most likely to act as a good catalyst due to its ability to adopt multiple oxidation states?

Correct Answer: A

Q22.Which of the following transition metals is known for its catalytic properties in the Haber process?

Correct Answer: A

Q23.Which of the following transition metals has the highest enthalpy of atomisation?

Correct Answer: B

Q24.In the preparation of potassium dichromate from iron chromite ore, what is the effect of increasing pH on a solution of potassium dichromate?

Correct Answer: B

Q25.Given the electronic configuration of a transition metal in its ground state as 3d⁵ 4s¹, which element does this configuration represent?

Correct Answer: B

Q26.Why are transition metals often used as catalysts?

Correct Answer: B

Q27.Which of the following transition metals is known to form interstitial compounds with small atoms like hydrogen, carbon, or nitrogen?

Correct Answer: A

Q28.Which transition metal exhibits the largest number of oxidation states, ranging from +2 to +7, due to its ability to lose different numbers of d electrons?

Correct Answer: B

Q29.What is the primary reason for the lanthanoid contraction?