Online Short Notes 1 => Chapter 1 (SOLID STATE) 12th class

These are Short Notes 1 on Chapter 1 named “Solid State”. Go through it to increase your knowledge of chemistry and revise it as much for examinations like CBSE Board, CBSE NEET, CSIR NET, GRE etc.

As we know that matter exists in different physical states under different conditions of temperature and pressure. For example, solid state, liquid , gases , plasma and BEC etc.


Introduction:

1. The state of matter whose m.p. is above room temp is found in solid state. Their constituent particles are held strongly.

2. Type of solid (Based on arrangement of particle) :
1 : Crystalline
2 :Amorphous

3. Crystalline solids have regular arrangement of constituent particles throughout, melting point is sharp, anisotropic in nature and give clear cut cleavage.

4. Amorphous solids have no regular arrangement, range of m.p., isotropic in nature. They do not exhibit cleavage property.

5. Amorphous silica is used in photovoltaic cells(Device for converting light into electricity, solar panels etc. ).

6. Space lattice is the regular 3D arrangement of constituent particles in the crystalline solid.

7. Smallest repeating unit in a space lattice is called unit cell.

8. There are 4 types of unit cells, 7 crystal systems and 14 bravais lattices.

9. Types of unit cell                No. of atoms per unit cell
i.   Simple cubic unit cell               8 x 1/8 = 1
ii.  FCC (Face centered cubic)       8 x 1/8 + 6 x1/2 = 4
iii. BCC (Body centered cubic)    8 x 1/8 + 1 x1 =2

10. Hexagonal close packing and cubic close packing have only 74% of the available space occupied.

11. Packing efficiency =
volume occupied by spheres (Particles) / volume of unit cell x 100

12. For simple cubic unit cell the p.f. = 1 x 4 / 3 x πr³ / 8 x r³ x 100 = 52.4 %

13. The packing efficiency in fcc = 4 x 4/3 x πr³/16 x 2 1/2 r³ x 100 = 74 %

14. The packing efficiency in bcc =2 x 4/3 x πr³/64 x 33/2 r³ x 100 = 68 %

15. The packing efficiency in hcp =74%

16. Packing efficiency in bcc arrangement in 68% and simple cubic unit cell is 52.4%.

17. Unoccupied spaces in solids are called interstitial voids or interstitial sites.

18. Two important interstitial voids are (I). Tetrahedral void and (II). Octahedral void.

19. Radius ratio is the ratio of radius of Cation to the radius of anion.
a. For tetrahedral arrangement(Cordination Number=4), radius ratio
 =0.225-0.414
b. For octahedral arrangement(Cordination Number=6), radius ratio
= 0.414-0.732

20. No. of tetrahedral void = 2 x N (N=No. of particles)

21. No. of octahedral void = N

22. Formula of a compound depends upon arrangement of constituent of particles.

23. Density of unit cell
   p= Z x M/a³ x N_A
  p =density, M=Molar mass, a=side of unit cell, N_A=6.022 x 10²³

24. The relationship between edge length and radius of atom and interatomic or interionic distance for different types of unit is different as given below
a.  Simple cubic unit cell,    a =  2R
b.  f c c,   a=4R√ 2
c.  b c c,   a=4R√3 (where R = Radius of sphere)

25. Imperfection is the ir-regularty in the arrangement of constituent particles.

26. Point defect or Atomic defect => it is the deviation from ideal arrangement of constituent atom. Point defects are two types (a) Vacancy defect (b) Interstitial defect

27. Vacancy defect lowers the density and

28. Interstitial defect increases the density of crystal.

29. Point defects in the ionic crystal may be classified as:
a. Stoichiometric defect (Ratio of cation and anion is same).
b. Non Stoichiometric defect (Ratio of cation and anion gets disturbed).
c. Impurity defects (due to presence of some impurity ions at the lattice sites)

30. Schottky defect lowers the density of crystal it arises due to missing of equal no. of cations of anions from lattice sites e.g. NaCl.

31. Frenkel defect is the combination of vacancy and interstitial defects. Cations leave their actual lattice sites and come to occupy the interstitial spaces. Density remains the same eg. AgCl, AgBr, ZnS.

32. Non stoichiometric defect
a. Metal excess defect due to anion vacancy.
b. Metal excess defect due to presence of interstitial cation.
c. Metal deficiency due to absence of cation.