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Atomic Structure Lecture -3 12 june (1).pptx
- 1. LECTURE Structure of Atom BohrModel & EM Waves 3
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- 3. r = ..to beLearnt !! 1. RADIUS of various orbits (Shell) n2 h2 42 mkZe2 Bohr’s Model Atomic Structure Lecture- 3 The formula is applicable for hydrogen and hydrogen like species i.e. species containing single electron.
- 4. ..to be Learnt!! 1. Speed of electron in various orbits (Shell) v = Bohr’s Model Atomic Structure Lecture- 3 The formula is applicable for hydrogen and hydrogen like species i.e. species containing single electron.
- 5. Energy of anelectron : Bohr’s model Atomic Structure Lecture- 3
- 6. Energy of anelectron : Bohr’s model Atomic Structure Lecture- 3
- 7. Energy of anelectron : Bohr’s model Atomic Structure Lecture- 3
- 8. To be remembered (i)K.E. = on increasing r, k.E. decreases. (ii) P.E. = on increasing r, P.E. increases. (ii) T.E. = on increasing r, total TE increases. kZe2 2r 1 r i.e. k.E –kZe2 2r –1 r i.e. P.E –kZe2 2r 1 r i.e. E – Bohr’s model Atomic Structure Lecture- 3
- 9. 1. What isthe energy of the electron in He+ in ground state ? Bohr’s model Atomic Structure Lecture- 3
- 10. 2. Calculate theenergy associated with the second orbit of He+. What is the radius of this orbit ? Bohr’s model Atomic Structure Lecture- 3
- 11. 3. Calculate theenergy associated with the first ,second third and fourth bohr orbit of H. Bohr’s model Atomic Structure Lecture- 3
- 12. Energy difference betweentwo energy levels For H: E2 – E1 = – 3.4 + 13.6 = 10.2 eV E3 – E2 = – 1.51 + 3.4 = 1.89 eV E4 – E3 = – 0.85 + 1.51 = 0.66 eV E5 – E4 = – 0.54 + 0.85 = 0.16 eV i.e. (E2 – E1) > (E3 – E2) > (E4 – E3) > (E5 – E4)….. n2 n1 2 2 n n E – E –13.6 Z2 1 – 1 2 1 Bohr’s model Atomic Structure Lecture- 3
- 13. SUCCESSES OF BOHR’SMODEL 1. Bohr’s model could explain the stability of an atom. 2. Bohr’s theory helped in calculating energy of an electron in a particular orbit of hydrogen. 3. Bohr’s model could explain the atomic spectrum of hydrogen. 4. Bohr’s model also accounts for the existence of so many lines in hydrogen spectrum. Bohr’s model Atomic Structure Lecture- 3
- 14. 4. The energyassociated with the first orbit of hydrogen atom is –2.18 × 10–18 J/atom. What is the energy associated with the fifth orbit ? Bohr’s model Atomic Structure Lecture- 3
- 15. 4th POSTULATE Ifthe e– remains in the stationary state then it does not lose energy. Such a state is called ground state (lowest energy state) Bohr’s model Atomic Structure Lecture- 3
- 16. 5th POSTULATE Eachstationary orbit is associated with definite amount of E therefore these orbits are also called as energy levels and are numbered as 1, 2, 3, 4, 5…… or K, L, M, N, O…… from the nucleus outwards. E1 < E2 < E3 < E4 < E5……. (E2 – E1) > (E3 – E2) > (E4 – E3) > (E5 – E4)…… Bohr’s model Atomic Structure Lecture- 3
- 17. 6th POSTULATE Theemission or absorption of energy in the form of radiation can occur only when e– jumps from one stationary state to another. E is absorbed when e– jumps from inner to outer orbit and emitted when e– moves from outer to inner orbit. Bohr’s model Atomic Structure Lecture- 3
- 18. QUANTISATION OF ENERGYAND BOHR’S MODEL Quantization means that a quantity cannot vary continuously to have any arbitrary values but can change only discontinuously to have some specific values. (a) Quantized Energy (b) Continuous change of energy Bohr’s model Atomic Structure Lecture- 3
- 19. E absorbed Ground StateExited State E released 1st excited state = 2nd orbit 2nd excited state = 3rd orbit & so on. IONIZATION ENERGY : Energy req. to librate an e– from ground state of an isolated atom. Bohr’s Model Atomic Structure Lecture- 3
- 20. 5. Find radiusratio of 1st & 3rd Bohr orbit of He. Atomic Structure Lecture- 3 Can u Crack it!
- 21. 6. Find velocityof e– on 3rd energy level of He. Atomic Structure Lecture- 3 Can u Crack it!
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- 40. Yellow light emittedfrom a sodium lamp has a wavelength () of 580 nm. Calculate the frequency and wave number of this light. Atomic Structure Lecture- 3 Can u Crack it!
- 41. 5. The frequencyof strong yellow line in the spectrum of sodium is 5.09 × 1014 sec–1. Calculate the wavelength of the light in nanometer. Atomic Structure Lecture- 3 Can u Crack it!
- 42. 6. The wavelengthof a spectral line of cesium is 460 nm. Calculate the frequency of the line. Atomic Structure Lecture- 3 Can u Crack it!
- 43. 7. A certainradio station broadcasts on a frequency of 980 kHz (kilohertz). What is the wavelength of electromagnetic radiation broadcast by the ratio station ? Atomic Structure Lecture- 3 Can u Crack it!
- 44. 8. Calculate thewave number of radiation having a frequency of 4×1011 kHz. Atomic Structure Lecture- 3 Can u Crack it!
- 45. 9. The wavelengthof blue light is 480 nm. Calcualte the frequency and wave number of this light. Atomic Structure Lecture- 3 Can u Crack it!
- 46. 10. Calculate (i)wave number and (ii) frequency of yellow radiation having wavelength 5800 Å. Atomic Structure Lecture- 3 Can u Crack it!
- 47. 11. Calculate thecompare the energies of two radiations, one with a wavelength of 400 nm and the other with 800 nm. Atomic Structure Lecture- 3 Can u Crack it!
- 48. 12. Yellow lightemitted from a sodium lamp has a wavelength () of 580 nm. Calculate frequency (v) and wave number ( v ) of the yellow light. Atomic Structure Lecture- 3 Can u Crack it!
- 49. 13. The wavenumber of a beam of light is 400 cm–1. What is the wavelength of the light in nanometers ? Also find out frequency of the light. Atomic Structure Lecture- 3 Can u Crack it!