Chapter 7 of 16
Revision Notes
Elements of Groups 16, 17 and 18 — Revision Notes
Maharashtra Board · Class 12 · Chemistry
Elements of Groups 16, 17 and 18 revision notes for Maharashtra Board Class 12 Chemistry: 4 topics in quick points.
45 questions25 flashcards5 concepts
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Key Topics to Revise
1
Electronic Configuration and General Properties
- Group 16: ns²np⁴ (need 2 electrons to complete octet)
- Group 17: ns²np⁵ (need 1 electron to complete octet)
- Group 18: ns²np⁶ (complete octet, chemically inert)
2
Anomalous Behavior of First Elements
- Oxygen anomalies: diatomic (O₂), paramagnetic, shows -2, -1, +2 oxidation states only
- H₂O is liquid due to hydrogen bonding while other hydrides are gases
- Fluorine anomalies: highest electronegativity, shows only -1 oxidation state
3
Chemical Reactivity and Oxidation States
- Group 16: Common oxidation states -2, +2, +4, +6 (except O: -2, -1, +2)
- Group 17: F shows -1 only; others show -1, +1, +3, +5, +7
- Group 18: Generally zero valent; Xe shows +2, +4, +6, +8
4
Allotropy and Important Compounds
- Sulfur allotropes: Rhombic (α-S₈, stable <369K) and Monoclinic (β-S₈, stable >369K)
- Both have S₈ puckered ring structure
- Ozone (O₃): Angular molecule, powerful oxidizing agent, protects from UV rays
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Full NotesKey Concepts
Group 16 has ns²np⁴ configurationOxygen is diatomic (O₂) and paramagneticIndustrial preparation involvesPrepared by silent electric discharge throughHalogens (X₂) show decreasing reactivity down
Frequently Asked Questions
What are the important topics in Elements of Groups 16, 17 and 18 for Maharashtra Board Class 12 Chemistry?
Key topics in Elements of Groups 16, 17 and 18 include Electronic Configuration and General Properties, Anomalous Behavior of First Elements, Chemical Reactivity and Oxidation States, Allotropy and Important Compounds. Study these first, then practise questions on each for the Maharashtra Board Class 12 board exam.
How should I revise Elements of Groups 16, 17 and 18 for the Maharashtra Board Class 12 board exam?
Learn the core ideas first, then work through the 45 practice questions on Elements of Groups 16, 17 and 18. Revise definitions regularly and use flashcards for quick recall before the exam.
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