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Chemistry formula for class 12 chapter- Solid state

Chemistry Formulas


Property Crystalline variety      
    Molecular Ionic Covalent Metallic
1. Unit occupying the lattice point Vander Waals or dipole-dipole interactions +ve or –ve ion Atoms +ve ions in a sea of electrons.
2. Forces of attraction between the units. Vander Waals or dipole-dipole interactions Electrostatic forces Shared electron pairs Attractions between metal ions and sea of electrons
3. Melting points & Boiling points Low High Very High Moderate very high
4. Electrical conductivity Extremely low High in molten or dissolved state Usually insulators Good conductors
5. (a) Hardness Soft usually Hard & brittle Very hard May be soft or hard giant molecules.
  (b) Solubility In non-polar solvents In polar solvents Insoluble in ordinary solvents ––
6. Examples H2O; CO2; H2P4;S NaCl; KNO3 Na2SO4 CaCO2 Diamond; graphite Si; SiC Na, K, Mg; Al, Cu, Fe, Ag


S.No Radius ratio ( = rsmall/rlarge) Geometric shape of the crystal formed Coordination number of the ion
1. upto 0015 Linear 2
2. 0.15 to 0.22 Trigonal planar 3
3. 0.22 to 0.41 Tetrahedral 4
4. 0.41 to 0.73 Square pyramidal 4
5. 0.41 to 0.73 Octohedral 6
6. > 0.73 Cubic 8

Arrangements of (metal atoms) spheres in space :

Simple cube :

Spheres can be arranged in a layer such that each metal atom is in touch with four other atoms.

Bravis Lattices

Combining the shapes of crystals (obtained by repitation of unit cell in 3 dimensions) and the fundamental laws of crystallogram give that there are only 14 basic arrangements known as Bravais lattices.


The atoms, molecules, or ions making up the crystal are present at the lattice points and are represented by points. There are three types of lattice points.

  • Points at corner: The lattice points at the corner of a unit cell are shared by 8 Vicinal unit cells. Its contribution is 1/8.
  • Points at face center: The lattice point at the face center of a unit cell is shared by 2 adjacent unit cells. Its contribution is 1/2.
  • Points at body center: The lattice point at the body centered of a unit cell belongs entirely to that cell. Its contribution is 1.


Empty spaces formed by the three-dimensional layers are called voids or holes.

Octahedral voids

The vacant space between a group of three spheres in one layer and another set of three spheres in a subsequent layer.

Tetrahedral void

A hole formed by the three spheres of a layer in contact with each other and a sphere of the next layer. The hole is called a tetrahedral void.

Types of defects

There are two types of defects if we classify them broadly: point defects and line defects. Line defects are also called dislocations.

  1. Stoichiometric defects: These are point defects that do not disturb the stoichiometry (composition) of the solid. They are also called intrinsic or thermodynamic defects.
  2. Impurity defects: CaCl2 or SrCl2 is added to molten NaCl, crystallized. Some of the Na+ ions are replaced by Ca2+ ions or Sr2+. Each Ca2+ or Sr2+ ions replaces two Na+ ions. It occupies the site of one of the ions, and the other site remains vacant. The number of cationic vacancies equals the number of bivalent cations added. A similar example of an impurity defect is the addition of CdCl2 to AgCl.
  3. Non-stoichiometric defects: Those defects which lead to a change in the composition of solids are called non-stoichiometric defects. They contain constituting particles is a non-stoichiometric ratio, e.g., Fe0.93O1.0, Ni0.94O1.00 are examples of non-stoichiometric compounds.

Chemistry Formula Sheet for chapter - Solid state is prepared by expert of Physics Wallah and consist of Solid state formula use in these chapter. Do find the detail NCERT Solutions for Class 12 Chemistry prepared by expert faculty of Physics Wallah.

If any students need to take the online test to check their concepts or undertstanding for their board exams or competative exams then they can visit Quiz for Solid State.

Also Check

  1. Important questions of Solid State
  2. MCQ of Solid State


Download free PDF sheet which consist of Solid State Formula from the link given below


Chemistry formula for class 12 chapter- Solid state

Chemistry formula for class 12 chapter- Solid state

Chemistry formula for class 12 chapter- Solid state

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