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Lecture 7: D and F Block Elements
Jun 10, 2024
Lecture 7 of D and F Block Elements
Introduction
Welcome to Physics Wallah's lecture 7 on D and F block elements.
Ensure to solve and review all provided lectures, questions, and DPPS for high marks.
Lecture focus: Potassium permanganate and F block elements.
Review from Last Lecture
Previous topics: Dioxides, Potassium Dichromate.
Importance of thorough understanding and solving DPPS.
Potassium Dichromate: Vital lab chemical, often recurring in exams.
Current Lecture: Potassium Permanganate (KMnO4)
Appearance
KMnO4: Purple crystal, KMnO4 formula.
Common use in titrations (oxidizing agent).
Preparation Methods
1. Commercial Method
Alkaline oxidative fusion of MnO2.
Reaction with KOH and O2:
MnO2 + KOH + O2 → K2MnO4 + H2O
Manganate (green), converted to Permanganate by electrolysis or chemical oxidation.
Reaction with KNO3 and other oxidizing agents.
2. Electrolytic Oxidation
K2MnO4 electrolysis gives KMnO4 and other products.
Reaction formula: MnO42- + H2O → MnO4- + MnO2.
Properties
Color
: Dark purple, needle-like crystalline solid with metallic luster.
Decomposition
: Decomposes at 513K.
Oxidizing Agent
: Strong oxidizing in acidic, neutral, and alkaline mediums.
Acidic: MnO4- + 8H+ + 5e- → Mn2+ + 4H2O
Basic: MnO4- + e- → MnO42-
Neutral: MnO4- + 2H2O + 3e- → MnO4- + MnO2 + 4OH-
Uses
Analytical chemistry (lab use).
Bleaching agent.
Decontaminating water.
Organic synthesis applications.
Oxidizing agent in various reactions (e.g., with NO2-, C2O4 2-, Br-).
Introduction to F-Block Elements
General Information
Position: Bottom of the periodic table.
Split into lanthanoids (4f-series) and actinoids (5f-series).
Named based on the last electron entering the 'f' subshell.
Classified as inner transition elements.
Lanthanoids
Period 6, group 3 of periodic table.
Elements 58 (Ce) to 71 (Lu).
General electron configuration: [Xe] 4f^1-14 5d^0-1 6s^2.
F-electrons fill antispenultimate shell.
Actinoids
Period 7, group 3 of periodic table.
Elements 90 (Th) to 103 (Lr).
General electron configuration: [Rn] 5f^1-14 6d^0-1 7s^2.
Filling of 5f sub-shell.
Electronic Configurations of Lanthanoids
La: [Xe] 5d^1 6s^2
Ce: [Xe] 4f^1 5d^1 6s^2
Pr: [Xe] 4f^3 6s^2
Nd: [Xe] 4f^4 6s^2
Sm: [Xe] 4f^6 6s^2
Eu: [Xe] 4f^7 6s^2
Gd: [Xe] 4f^7 5d^1 6s^2
Tb: [Xe] 4f^9 6s^2
Dy: [Xe] 4f^10 6s^2
Ho: [Xe] 4f^11 6s^2
Er: [Xe] 4f^12 6s^2
Tm: [Xe] 4f^13 6s^2
Yb: [Xe] 4f^14 6s^2
Lu: [Xe] 4f^14 5d^1 6s^2
Lanthanoid Contraction
Trend: Decrease in size from Ce to Lu.
Due to poor shielding effect of 4f electrons.
Consequences:
Similarity in ionic radii of 4d and 5d block elements.
Difficulty in separation of lanthanoids.
Affect on atomic size across periods.
Higher nuclear charge results in smaller ionic radii.
Quiz and Homework
Revise and memorize the electronic configurations and properties discussed.
Solve given problems on Lanthanoid Contraction and properties of KMnO4.
Conclusion
Finish review of lanthanoid series in next class.
Preview of next chapter: Coordination Compounds.
Emphasis on regular study and daily problem solving.
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