#crystal field theory

CHEMISTRY

What is the number of unpaired electrons in [Mn(Hâ‚‚O)6]^{2+ ?

Given: What is the number of unpaired electrons in [Mn(H₂O)6]^{2+ ? These values define the system as per NCERT data. Formula: Mn²⁺ ( d⁵ ) with weak field H₂O in an octahedral field is high spin ( t_{2g³ e_g² ), with 5 unpaired electrons.. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: Substituting values like 1.2 × 10⁻⁵, 236 J kg⁻¹ K⁻¹, CH₃CH₂NH₂ etc. into the formula and simplifying step by step. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Some Basic Concepts, Structure of Atom and Periodicity, Topic: Mole concept, atomic models and periodic trends.

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CHEMISTRY

What is the crystal field splitting parameter in a tetrahedral field compared to an octahedral field for the same metal

For the same metal and ligands, the tetrahedral splitting ( Δ_t ) is 4/9 of the octahedral splitting ( Δ_o ), due to fewer ligands and different geometry.

Ref: NCERT Chemistry Textbook for Class XI and XII, Chapter: Coordination Compounds and d Block Elements, Topic: Colour of [Ti(H₂O)₆]³⁺, d-d transition, crystal field theory.

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Werner's Theory and Definitions - Ligands Coordination Number

What is the ratio of eg to t2g electrons in [Fe(H₂O)6]2+ with Fe in +2 state? (Fe atomic number = 26)

Fe₂+ (d6), weak field H₂O, octahedral, high spin: t2g4 eg2. Ratio = 2 : 4 = 1 : 2.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Werner's Theory and Definitions - Ligands Coordination Number

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Nomenclature of Coordination Compounds

Which complex has a d5 metal ion with the maximum possible unpaired electrons in a tetrahedral field?

[MnCl₄]2− (Mn₂+, d5) in a tetrahedral field with weak field Cl− is high spin (e2 t23), with 5 unpaired electrons.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Nomenclature of Coordination Compounds

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Nomenclature of Coordination Compounds

How many unpaired electrons are present in [Co(H₂O)6]3+? (Co atomic number = 27)

Co₃+ (d6) in [Co(H₂O)6]3+ (octahedral) with weak field H₂O is high spin: t2g4 eg2, giving 4 unpaired electrons.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Nomenclature of Coordination Compounds

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Isomerism - Optical Isomerism and Linkage Ionisation Solvate

Which complex has a metal ion with zero unpaired electrons in an octahedral field?

[Co(CN)6]3− (Co₃+, d6) with strong field CN− is low spin (t2g6), with 0 unpaired electrons.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Isomerism - Optical Isomerism and Linkage Ionisation Solvate

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Isomerism - Optical Isomerism and Linkage Ionisation Solvate

How many unpaired electrons are present in [CoF₆]3−? (Co atomic number = 27)

Co₃+ (d6) in [CoF₆]3− (octahedral) with weak field F− is high spin: t2g4 eg2, giving 4 unpaired electrons.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Isomerism - Optical Isomerism and Linkage Ionisation Solvate

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Isomerism - Optical Isomerism and Linkage Ionisation Solvate

Which complex has a d6 metal ion that is low spin in an octahedral field?

[Co(CN)6]3− (Co₃+, d6) with strong field CN− is low spin (t2g6).

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Isomerism - Optical Isomerism and Linkage Ionisation Solvate

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Isomerism - Geometrical Isomerism in Coordination Compounds

How many electrons occupy the t2g orbitals in [Cr(NH₃)6]3+? (Cr atomic number = 24)

Cr₃+ (d3) in [Cr(NH₃)6]3+ (octahedral) with moderate field NH₃ has t2g3, so 3 electrons.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Isomerism - Geometrical Isomerism in Coordination Compounds

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Isomerism - Geometrical Isomerism in Coordination Compounds

Which complex has a d4 metal ion with 2 unpaired electrons in an octahedral field?

[Mn(CN)6]3− (Mn₃+, d4) with strong field CN− is low spin (t2g4), 2 unpaired electrons.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Isomerism - Geometrical Isomerism in Coordination Compounds

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Crystal Field Theory - CFT and Crystal Field Splitting and CFSE

Which complex has the smallest crystal field splitting energy (Δo) among the following?

[FeCl₆]4− has Cl−, the weakest field ligand, giving the smallest Δo.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Crystal Field Theory - CFT and Crystal Field Splitting and CFSE

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Crystal Field Theory - CFT and Crystal Field Splitting and CFSE

Which complex has a higher crystal field splitting energy (Δo) with CN− ligands compared to NH₃ ligands?

[Fe(CN)6]4− has CN−, a stronger field ligand than NH₃, resulting in a larger Δo.

Ref: NCERT Class 12 Chemistry > Chapter 5: Coordination Compounds > Topic: Crystal Field Theory - CFT and Crystal Field Splitting and CFSE

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