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Similar to Class 12, subject chemistry chapter name solid state, topic name - electrical and magnetic properties of solids
Class 12, subject chemistry chapter name solid state, topic name - electrical and magnetic properties of solids
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- 3. RECAP ✓ Imperfections inSolids • Stoichiometric Defects • Impurity Defects • Non-Stoichiometric Defects
- 4. Electrical properties inSolids Solids are classified into 3 types based on their conductivities: i) Conductors: Conductivity range 104 to 107 ohm-1 m-1. ii) Insulators: Conductivity range 10-20 to 10-10 ohm-1 m-1. iii) Semiconductors: Conductivity range 10-6 to 104 ohm-1 m-1.
- 5. Band theory E N E R G Y Unfilled bands Filledbands 3s 3p 3s 3p Single atom 5 atoms in proximity Conduction band Valence band
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- 7. Doping • The conductivityof intrinsic semiconductors can be increased by adding appropriate amount of suitable impurity - Doping • Electrical conductivity of semiconductors increases with rise in temperature, since more electrons can jump to conduction band. • Substances like silicon and germanium show this type of behavior – intrinsic semiconductors
- 8. Doping a) Doping withelectron-rich impurities n-type semiconductor b) Doping with electron-deficit impurities p-type semiconductor
- 9. a) Doping withelectron-rich impurities n-type semiconductor Image reference NCERT textbook
- 10. b) Doping withelectron-deficit impurities p-type semiconductor Image reference NCERT textbook
- 11. Applications of n-typeand p-type semiconductors • Diode - rectifier • Transistor – detect or amplify radio or audio signals
- 12. Magnetic properties inSolids Electron’s magnetic moment originates from types of motion: i) It’s orbital motion around the nucleus ii) It’s spin around its own axis Image reference NCERT textbook
- 13. Magnetic properties inSolids • Magnitude of this magnetic moment is measured in the unit called Bhor magneton μB. It is equal to 9.27 × 10-24Am2. • Movement of charges creates magnetic moment. Thus, each electron has permanent spin and an orbital magnetic moment associated with it. Image reference NCERT textbook
- 14. Based on theirmagnetic properties substances can be classified into 5 categories: i) Paramagnetic ii) Diamagnetic iii) Ferromagnetic iv) Antiferromagnetic v) Ferrimagnetic • In solid state, the metal ions of certain substances are grouped together into small regions called domains. Thus, each domain acts as tiny magnet
- 15. Paramagnetisim • Substances areweakly attracted by magnetic field. Normal paramagnetic field Magnetic field applied Magnetic field removed
- 16. Paramagnetisim • Temporary magnetism •Due to the presence of one or more unpaired electrons which are attracted by the negative field. • O2, Cu2+, Fe3+, Cr3+
- 17. Diamagnetism • Substances areweakly repelled by magnetic field. No Magnetic domain H Magnetic field
- 18. Diamagnetism • H2O, NaCland C6H6 • Pairing of electrons cancels their magnetic moments and they lose their magnetic character. • Due to the pairing of electrons, all electrons are paired and no unpaired electrons are present.
- 19. Ferromagnetism • Attracted verystrongly by magnetic field Applied magnetic field • Permanent magnetism even in the absence of magnetic field No applied magnetic field
- 20. Ferromagnetism • This typeof magnetism due to the spontaneous alignment of magnetic moments is due to unpaired electrons in the same direction. • Fe, Ni, Co and CrO2
- 21. Antiferromagnetism No net magnetization No applied magnetic field •Due to equal number of magnetic moments in opposite direction they cancel out each other.
- 22. Antiferromagnetism • Substance whichare expected to possess ferromagnetism on the basis of unpaired electrons but possess zero magnetic moment.
- 23. Ferrimagnetism • Weakly attractedby magnetic field • Substances which are expected to possess large magnetism on the basis of unpaired electrons but have small magnetic momentum.
- 24. Ferrimagnetism • Due tounequal moments in opposite direction resulting in same net magnetic moment. • On heating the substance loses their magnetism and convert to paramagnetic substance. • Fe3O4 (magnetite), MgFe2O4 and ZnFe2O4 (ferrites)