Chapter 3 of 15
Syllabus
p-Block Elements-I — Syllabus
Tamil Nadu Board · Class 12 · Chemistry
What p-Block Elements-I covers in Tamil Nadu Board Class 12 Chemistry: 4 topics, for the 2026-27 session. Topics include General Trends in p-Block.
44 questions30 flashcards5 concepts
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4 Topics · Tamil Nadu Board Class 12 Chemistry · 2026-27
Topics in p-Block Elements-I
1
General Trends in p-Block Elements
- General electronic configuration: ns², np¹⁻⁶ (n = 2 to 6)
- Each group has similar outer shell configuration; elements differ only in the value of 'n'
- Group 18 (ns²np⁶) has completely filled p orbitals — most stable, least reactive, hence called inert gases
2
Anomalous Behaviour of First Elements of p-Block Groups
- First member of EACH p-block group differs significantly from remaining members of the group
- Three main reasons: (i) Small size, (ii) High IE and high electronegativity, (iii) Absence of d-orbitals in valence shell
- Boron (Group 13): metalloid, not metal like Al, Ga, In, Tl. Shows diagonal relationship with Silicon
3
Group 13 — Boron Family: Occurrence, Physical and Chemical Properties
- Boron occurs as borates: Borax — Na₂[B₄O₅(OH)₄]·8H₂O and Kernite — Na₂[B₄O₅(OH)₄]·2H₂O
- Aluminium is the MOST ABUNDANT METAL in Earth's crust; chief ore: Bauxite (Al₂O₃·2H₂O)
- Ga, In, Tl occur as sulphides and in trace amounts
4
Borax [Na₂B₄O₇·10H₂O] — Preparation, Properties and Uses
- Borax = sodium salt of tetraboric acid
- Actual formula contains tetranuclear units [B₄O₅(OH)₄]²⁻ — known as prismatic form
- Three forms: Prismatic borax (Na₂B₄O₇·10H₂O), Jeweller's/Octahedral borax (Na₂B₄O₇·5H₂O), Borax glass (Na₂B₄O₇)
Key Concepts
pThe maximum oxidation state (group oxidationGenerallyIn Group 13Metallic character increases down a group
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What are the important topics in p-Block Elements-I for Tamil Nadu Board Class 12 Chemistry?
Key topics in p-Block Elements-I include General Trends in p-Block Elements, Anomalous Behaviour of First Elements of p-Block Groups, Group 13 — Boron Family: Occurrence, Physical and Chemical Properties, Borax [Na₂B₄O₇·10H₂O] — Preparation, Properties and Uses. Study these first, then practise questions on each for the Tamil Nadu Board Class 12 board exam.
How should I revise p-Block Elements-I for the Tamil Nadu Board Class 12 board exam?
Learn the core ideas first, then work through the 44 practice questions on p-Block Elements-I. Revise definitions regularly and use flashcards for quick recall before the exam.
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