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Syllabus

The Solid State — Syllabus

Telangana Open School (TOSS) · Class 12 · Chemistry

What The Solid State covers in Telangana Open School (TOSS) Class 12 Chemistry: 4 topics, for the 2026-27 session.

53 questions37 flashcards3 formulas & key relations5 concepts

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4 Topics · Telangana Open School (TOSS) Class 12 Chemistry · 2026-27

Topics in The Solid State

1

Classification of Solids

  • Solids are classified into crystalline and amorphous based on particle arrangement.
  • Crystalline solids have a regular, repeating 3D pattern (long-range order), while amorphous solids have only short-range order.
  • Crystalline solids are anisotropic (properties vary with direction), whereas amorphous solids are isotropic (same in all directions).
2

Close Packing in Solids

  • In solids, particles are closely packed to minimize empty space.
  • Two types of 2D packing: square (coordination number 4) and hexagonal (coordination number 6). Hexagonal is more efficient.
  • 3D packing arises from stacking 2D layers: ABAB… gives hexagonal close packing (hcp), ABCABC… gives cubic close packing (ccp).
3

Crystal Lattices and Unit Cells

  • A crystal lattice is a 3D arrangement of points representing particle positions.
  • A unit cell is the smallest repeating unit that generates the entire lattice.
  • Seven crystal systems exist; cubic is most common with three types: simple (SC), body-centered (BCC), face-centered (FCC).
4

Structures of Ionic Solids and Radius Ratio

  • Ionic solids adopt structures based on cation-anion size ratio (radius ratio).
  • Radius ratio = r⁺ / r⁻. Determines coordination number and structure type.
  • Common structures: NaCl (6:6 coordination, octahedral), CsCl (8:8, cubic), ZnS (4:4, tetrahedral).

Key Concepts

Central concept: The Solid State

Classification of SolidsProperties of SolidsClose Packed StructuresCrystal Lattices and Unit CellsStructures of Ionic SolidsDefects in SolidsMetallic Bonding

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Frequently Asked Questions

What are the important topics in The Solid State for Telangana Open School (TOSS) Class 12 Chemistry?
Key topics in The Solid State include Classification of Solids, Close Packing in Solids, Crystal Lattices and Unit Cells, Structures of Ionic Solids and Radius Ratio. Study these first, then practise questions on each for the Telangana Open School (TOSS) Class 12 board exam.
How should I revise The Solid State for the Telangana Open School (TOSS) Class 12 board exam?
Learn the core ideas first, then work through the 53 practice questions on The Solid State. Revise definitions regularly and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

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All Telangana Open School (TOSS) Class 12 Chemistry Syllabus

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