Ch 04 - The d-and f-Block Elements12th Chemistry
Definition of Transition Elements
Why are Zinc, Cadmium, and Mercury strictly excluded from being classified as 'transition elements' despite physically belonging to the d-block?
Why are Zinc, Cadmium, and Mercury strictly excluded from being classified as 'transition elements' despite physically belonging to the d-block?
The Core Principle:
To be classified as a transition element, an element MUST possess incompletely filled d-orbitals in either its ground state or in any of its common oxidation states.
The Exception:
- Zinc (Zn), Cadmium (Cd), and Mercury (Hg) have completely filled d-orbitals () in both their ground state and their standard oxidation states (e.g., is ).
- Because they lack partially filled d-orbitals, they do not show typical transition metal properties (like variable valency or coloured ions) and are thus excluded from this classification.
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Zn, Cd, Hg are '10/10' full, so they transition out of the club.
General Electronic Configuration of d-Block
General Electronic Configuration of d-Block
State the general mathematical representation for the outer electronic configuration of d-block transition elements.
Variables & Units:
- n = Principal quantum number of the outermost shell (dimensionless)
- (n-1) = Penultimate shell (dimensionless)
- d, s = Subshells (dimensionless)
Conditions/Notes:
- The subshell is progressively filled as atomic number increases.
- Notable Exception: Palladium (Pd, Z=46) completely breaks this rule with a configuration of .
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Variable Oxidation States
Transition metals exhibit a wide range of oxidation states. What determines the highest possible oxidation state an element can achieve in a specific 3d series?
Transition metals exhibit a wide range of oxidation states. What determines the highest possible oxidation state an element can achieve in a specific 3d series?
Determining the Maximum Oxidation State:
- The maximum oxidation state is theoretically equal to the sum of the -electrons and the unpaired -electrons.
- It increases from (+3) to (+7) in the 3d series because the number of unpaired electrons increases to a maximum of 5 in .
- After , pairing of d-electrons begins, meaning fewer electrons are available for bonding, and the maximum oxidation state steadily decreases towards (+2).
Note: The highest oxidation states are usually stabilized only in compounds bonded with highly electronegative elements like Oxygen (O) and Fluorine (F).
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Also in this chapter
42 more cards to study in Prism
- 4Interstitial Compounds
- 5Alloy Formation Rules
- 6Complex Formation Ability
- 7Formation of Coloured Ions
- 8Catalytic Properties of d-Block Elements
- 9Anomalous Configurations of Cr and Cu
- 10Atomic Radii Trends in a Transition Series
- 11Spin-Only Magnetic Moment Formula
- 12Melting and Boiling Points of Transition Metals
- 13Trends in Ionisation Enthalpies
- 14Bonding Nature and Oxidation States
- 15Covalent and Acidic Higher Oxides
- 16The Copper Anomaly in Electrode Potentials
- 17Aqueous Stability: Cu+ vs Cu2+
- 18Preparation of Sodium Chromate (Step 1 of Dichromate Prep)
- 19Disproportionation in Transition Metals
- 20Chromate-Dichromate pH Interconversion
- 21Redox Behaviour of d4 Species (Cr2+ vs Mn3+)
- 22Oxidising Action of Dichromate (Acidic)
- 23Preparation of Potassium Manganate (Step 1 of Permanganate Prep)
- 24Quenching of Orbital Angular Momentum
- 25Oxidising Action of Permanganate (Acidic)
- 26Oxidising Action of Permanganate (Neutral/Faintly Alkaline)
- 27Structures of Chromate and Dichromate Ions
- 28General Electronic Configuration of Actinoids
- 29Manganate vs Permanganate Ions
- 30The Lanthanoid Contraction
- 31Consequences of Lanthanoid Contraction
- 32Oxidation States of Lanthanoids
- 33Variable Oxidation States of Actinoids
- 34Thermal Decomposition of Potassium Permanganate
- 35Actinoids: Bonding Participation of 5f Electrons
- 36Chromyl Chloride Test
- 37Actinoid Contraction vs Lanthanoid Contraction
- 38Lanthanoids vs Actinoids: Complex Formation & Oxocations
- 39Lanthanoids vs Actinoids: Basicity & Stability
- 40Composition and Uses of Mischmetal
- 41Permanganate Oxidation of Oxalate (Acidic)
- 42d-Block Catalysts in the Chemical Industry
- 43Permanganate Oxidation of Thiosulphate (Neutral/Alkaline)
- 44Transition Elements in Photography
- 45The Coinage Metals
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