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2239-2242
6 10 ) Z 1 2 10 J C C d − × × = × = 3 84 × 10–16 Z m The atomic number of foil material gold is Z = 79, so that d (Au) = 3 0 × 10–14 m = 30 fm
9
2240-2243
2 10 J C C d − × × = × = 3 84 × 10–16 Z m The atomic number of foil material gold is Z = 79, so that d (Au) = 3 0 × 10–14 m = 30 fm (1 fm (i
9
2241-2244
84 × 10–16 Z m The atomic number of foil material gold is Z = 79, so that d (Au) = 3 0 × 10–14 m = 30 fm (1 fm (i e
9
2242-2245
0 × 10–14 m = 30 fm (1 fm (i e fermi) = 10–15 m
9
2243-2246
(1 fm (i e fermi) = 10–15 m ) The radius of gold nucleus is, therefore, less than 3
9
2244-2247
e fermi) = 10–15 m ) The radius of gold nucleus is, therefore, less than 3 0 × 10–14 m
9
2245-2248
fermi) = 10–15 m ) The radius of gold nucleus is, therefore, less than 3 0 × 10–14 m This is not in very good agreement with the observed result as the actual radius of gold nucleus is 6 fm
9
2246-2249
) The radius of gold nucleus is, therefore, less than 3 0 × 10–14 m This is not in very good agreement with the observed result as the actual radius of gold nucleus is 6 fm The cause of discrepancy is that the distance of closest approach is considerably larger than the sum of the radii of the gold nucleus and the a-particle
9
2247-2250
0 × 10–14 m This is not in very good agreement with the observed result as the actual radius of gold nucleus is 6 fm The cause of discrepancy is that the distance of closest approach is considerably larger than the sum of the radii of the gold nucleus and the a-particle Thus, the a-particle reverses its motion without ever actually touching the gold nucleus
9
2248-2251
This is not in very good agreement with the observed result as the actual radius of gold nucleus is 6 fm The cause of discrepancy is that the distance of closest approach is considerably larger than the sum of the radii of the gold nucleus and the a-particle Thus, the a-particle reverses its motion without ever actually touching the gold nucleus 12
9
2249-2252
The cause of discrepancy is that the distance of closest approach is considerably larger than the sum of the radii of the gold nucleus and the a-particle Thus, the a-particle reverses its motion without ever actually touching the gold nucleus 12 2
9
2250-2253
Thus, the a-particle reverses its motion without ever actually touching the gold nucleus 12 2 2 Electron orbits The Rutherford nuclear model of the atom which involves classical concepts, pictures the atom as an electrically neutral sphere consisting of a very small, massive and positively charged nucleus at the centre surrounded by the revolving electrons in their respective dynamically stable orbits
9
2251-2254
12 2 2 Electron orbits The Rutherford nuclear model of the atom which involves classical concepts, pictures the atom as an electrically neutral sphere consisting of a very small, massive and positively charged nucleus at the centre surrounded by the revolving electrons in their respective dynamically stable orbits The electrostatic force of attraction, Fe between the revolving electrons and the nucleus provides the requisite centripetal force (Fc) to keep them in their orbits
9
2252-2255
2 2 Electron orbits The Rutherford nuclear model of the atom which involves classical concepts, pictures the atom as an electrically neutral sphere consisting of a very small, massive and positively charged nucleus at the centre surrounded by the revolving electrons in their respective dynamically stable orbits The electrostatic force of attraction, Fe between the revolving electrons and the nucleus provides the requisite centripetal force (Fc) to keep them in their orbits Thus, for a dynamically stable orbit in a hydrogen atom Fe = Fc 2 2 2 0 1 4 ε = π e mv r r (12
9
2253-2256
2 Electron orbits The Rutherford nuclear model of the atom which involves classical concepts, pictures the atom as an electrically neutral sphere consisting of a very small, massive and positively charged nucleus at the centre surrounded by the revolving electrons in their respective dynamically stable orbits The electrostatic force of attraction, Fe between the revolving electrons and the nucleus provides the requisite centripetal force (Fc) to keep them in their orbits Thus, for a dynamically stable orbit in a hydrogen atom Fe = Fc 2 2 2 0 1 4 ε = π e mv r r (12 2) Rationalised 2023-24 Physics 296 Thus the relation between the orbit radius and the electron velocity is 2 2 0 4 e r εmv = π (12
9
2254-2257
The electrostatic force of attraction, Fe between the revolving electrons and the nucleus provides the requisite centripetal force (Fc) to keep them in their orbits Thus, for a dynamically stable orbit in a hydrogen atom Fe = Fc 2 2 2 0 1 4 ε = π e mv r r (12 2) Rationalised 2023-24 Physics 296 Thus the relation between the orbit radius and the electron velocity is 2 2 0 4 e r εmv = π (12 3) The kinetic energy (K) and electrostatic potential energy (U) of the electron in hydrogen atom are 2 2 2 0 0 1 and 2 8 4 e e K mv U r r ε ε = = = − π π (The negative sign in U signifies that the electrostatic force is in the –r direction
9
2255-2258
Thus, for a dynamically stable orbit in a hydrogen atom Fe = Fc 2 2 2 0 1 4 ε = π e mv r r (12 2) Rationalised 2023-24 Physics 296 Thus the relation between the orbit radius and the electron velocity is 2 2 0 4 e r εmv = π (12 3) The kinetic energy (K) and electrostatic potential energy (U) of the electron in hydrogen atom are 2 2 2 0 0 1 and 2 8 4 e e K mv U r r ε ε = = = − π π (The negative sign in U signifies that the electrostatic force is in the –r direction ) Thus the total energy E of the electron in a hydrogen atom is 2 2 0 0 8 4 e e E K U r r ε ε = + = − π π 2 0 8 e εr = − π (12
9
2256-2259
2) Rationalised 2023-24 Physics 296 Thus the relation between the orbit radius and the electron velocity is 2 2 0 4 e r εmv = π (12 3) The kinetic energy (K) and electrostatic potential energy (U) of the electron in hydrogen atom are 2 2 2 0 0 1 and 2 8 4 e e K mv U r r ε ε = = = − π π (The negative sign in U signifies that the electrostatic force is in the –r direction ) Thus the total energy E of the electron in a hydrogen atom is 2 2 0 0 8 4 e e E K U r r ε ε = + = − π π 2 0 8 e εr = − π (12 4) The total energy of the electron is negative
9
2257-2260
3) The kinetic energy (K) and electrostatic potential energy (U) of the electron in hydrogen atom are 2 2 2 0 0 1 and 2 8 4 e e K mv U r r ε ε = = = − π π (The negative sign in U signifies that the electrostatic force is in the –r direction ) Thus the total energy E of the electron in a hydrogen atom is 2 2 0 0 8 4 e e E K U r r ε ε = + = − π π 2 0 8 e εr = − π (12 4) The total energy of the electron is negative This implies the fact that the electron is bound to the nucleus
9
2258-2261
) Thus the total energy E of the electron in a hydrogen atom is 2 2 0 0 8 4 e e E K U r r ε ε = + = − π π 2 0 8 e εr = − π (12 4) The total energy of the electron is negative This implies the fact that the electron is bound to the nucleus If E were positive, an electron will not follow a closed orbit around the nucleus
9
2259-2262
4) The total energy of the electron is negative This implies the fact that the electron is bound to the nucleus If E were positive, an electron will not follow a closed orbit around the nucleus 12
9
2260-2263
This implies the fact that the electron is bound to the nucleus If E were positive, an electron will not follow a closed orbit around the nucleus 12 3 ATOMIC SPECTRA As mentioned in Section 12
9
2261-2264
If E were positive, an electron will not follow a closed orbit around the nucleus 12 3 ATOMIC SPECTRA As mentioned in Section 12 1, each element has a characteristic spectrum of radiation, which it emits
9
2262-2265
12 3 ATOMIC SPECTRA As mentioned in Section 12 1, each element has a characteristic spectrum of radiation, which it emits When an atomic gas or vapour is excited at low pressure, usually by passing an electric current through it, the emitted radiation has a spectrum which contains certain specific wavelengths only
9
2263-2266
3 ATOMIC SPECTRA As mentioned in Section 12 1, each element has a characteristic spectrum of radiation, which it emits When an atomic gas or vapour is excited at low pressure, usually by passing an electric current through it, the emitted radiation has a spectrum which contains certain specific wavelengths only A spectrum of this kind is termed as emission line spectrum and it EXAMPLE 12
9
2264-2267
1, each element has a characteristic spectrum of radiation, which it emits When an atomic gas or vapour is excited at low pressure, usually by passing an electric current through it, the emitted radiation has a spectrum which contains certain specific wavelengths only A spectrum of this kind is termed as emission line spectrum and it EXAMPLE 12 3 Example 12
9
2265-2268
When an atomic gas or vapour is excited at low pressure, usually by passing an electric current through it, the emitted radiation has a spectrum which contains certain specific wavelengths only A spectrum of this kind is termed as emission line spectrum and it EXAMPLE 12 3 Example 12 3 It is found experimentally that 13
9
2266-2269
A spectrum of this kind is termed as emission line spectrum and it EXAMPLE 12 3 Example 12 3 It is found experimentally that 13 6 eV energy is required to separate a hydrogen atom into a proton and an electron
9
2267-2270
3 Example 12 3 It is found experimentally that 13 6 eV energy is required to separate a hydrogen atom into a proton and an electron Compute the orbital radius and the velocity of the electron in a hydrogen atom
9
2268-2271
3 It is found experimentally that 13 6 eV energy is required to separate a hydrogen atom into a proton and an electron Compute the orbital radius and the velocity of the electron in a hydrogen atom Solution Total energy of the electron in hydrogen atom is –13
9
2269-2272
6 eV energy is required to separate a hydrogen atom into a proton and an electron Compute the orbital radius and the velocity of the electron in a hydrogen atom Solution Total energy of the electron in hydrogen atom is –13 6 eV = –13
9
2270-2273
Compute the orbital radius and the velocity of the electron in a hydrogen atom Solution Total energy of the electron in hydrogen atom is –13 6 eV = –13 6 × 1
9
2271-2274
Solution Total energy of the electron in hydrogen atom is –13 6 eV = –13 6 × 1 6 × 10–19 J = –2
9
2272-2275
6 eV = –13 6 × 1 6 × 10–19 J = –2 2 ×10–18 J
9
2273-2276
6 × 1 6 × 10–19 J = –2 2 ×10–18 J Thus from Eq
9
2274-2277
6 × 10–19 J = –2 2 ×10–18 J Thus from Eq (12
9
2275-2278
2 ×10–18 J Thus from Eq (12 4), we have 2 18 0 2
9
2276-2279
Thus from Eq (12 4), we have 2 18 0 2 2 10 J 8 ε − = − = − × eπ E r This gives the orbital radius 2 9 2 2 19 2 18 0 (9 10 N m /C )(1
9
2277-2280
(12 4), we have 2 18 0 2 2 10 J 8 ε − = − = − × eπ E r This gives the orbital radius 2 9 2 2 19 2 18 0 (9 10 N m /C )(1 6 10 C) 8 (2)(–2
9
2278-2281
4), we have 2 18 0 2 2 10 J 8 ε − = − = − × eπ E r This gives the orbital radius 2 9 2 2 19 2 18 0 (9 10 N m /C )(1 6 10 C) 8 (2)(–2 2 10 J) e r E ε − − × × = − = − π × = 5
9
2279-2282
2 10 J 8 ε − = − = − × eπ E r This gives the orbital radius 2 9 2 2 19 2 18 0 (9 10 N m /C )(1 6 10 C) 8 (2)(–2 2 10 J) e r E ε − − × × = − = − π × = 5 3 × 10–11 m
9
2280-2283
6 10 C) 8 (2)(–2 2 10 J) e r E ε − − × × = − = − π × = 5 3 × 10–11 m The velocity of the revolving electron can be computed from Eq
9
2281-2284
2 10 J) e r E ε − − × × = − = − π × = 5 3 × 10–11 m The velocity of the revolving electron can be computed from Eq (12
9
2282-2285
3 × 10–11 m The velocity of the revolving electron can be computed from Eq (12 3) with m = 9
9
2283-2286
The velocity of the revolving electron can be computed from Eq (12 3) with m = 9 1 × 10–31 kg, 6 0 2
9
2284-2287
(12 3) with m = 9 1 × 10–31 kg, 6 0 2 2 10 m/s
9
2285-2288
3) with m = 9 1 × 10–31 kg, 6 0 2 2 10 m/s 4 e v εmr = = × π Rationalised 2023-24 297 Atoms consists of bright lines on a dark background
9
2286-2289
1 × 10–31 kg, 6 0 2 2 10 m/s 4 e v εmr = = × π Rationalised 2023-24 297 Atoms consists of bright lines on a dark background The spectrum emitted by atomic hydrogen is shown in Fig
9
2287-2290
2 10 m/s 4 e v εmr = = × π Rationalised 2023-24 297 Atoms consists of bright lines on a dark background The spectrum emitted by atomic hydrogen is shown in Fig 12
9
2288-2291
4 e v εmr = = × π Rationalised 2023-24 297 Atoms consists of bright lines on a dark background The spectrum emitted by atomic hydrogen is shown in Fig 12 5
9
2289-2292
The spectrum emitted by atomic hydrogen is shown in Fig 12 5 Study of emission line spectra of a material can therefore serve as a type of “fingerprint” for identification of the gas
9
2290-2293
12 5 Study of emission line spectra of a material can therefore serve as a type of “fingerprint” for identification of the gas When white light passes through a gas and we analyse the transmitted light using a spectrometer we find some dark lines in the spectrum
9
2291-2294
5 Study of emission line spectra of a material can therefore serve as a type of “fingerprint” for identification of the gas When white light passes through a gas and we analyse the transmitted light using a spectrometer we find some dark lines in the spectrum These dark lines correspond precisely to those wavelengths which were found in the emission line spectrum of the gas
9
2292-2295
Study of emission line spectra of a material can therefore serve as a type of “fingerprint” for identification of the gas When white light passes through a gas and we analyse the transmitted light using a spectrometer we find some dark lines in the spectrum These dark lines correspond precisely to those wavelengths which were found in the emission line spectrum of the gas This is called the absorption spectrum of the material of the gas
9
2293-2296
When white light passes through a gas and we analyse the transmitted light using a spectrometer we find some dark lines in the spectrum These dark lines correspond precisely to those wavelengths which were found in the emission line spectrum of the gas This is called the absorption spectrum of the material of the gas 12
9
2294-2297
These dark lines correspond precisely to those wavelengths which were found in the emission line spectrum of the gas This is called the absorption spectrum of the material of the gas 12 4 BOHR MODEL OF THE HYDROGEN ATOM The model of the atom proposed by Rutherford assumes that the atom, consisting of a central nucleus and revolving electron is stable much like sun-planet system which the model imitates
9
2295-2298
This is called the absorption spectrum of the material of the gas 12 4 BOHR MODEL OF THE HYDROGEN ATOM The model of the atom proposed by Rutherford assumes that the atom, consisting of a central nucleus and revolving electron is stable much like sun-planet system which the model imitates However, there are some fundamental differences between the two situations
9
2296-2299
12 4 BOHR MODEL OF THE HYDROGEN ATOM The model of the atom proposed by Rutherford assumes that the atom, consisting of a central nucleus and revolving electron is stable much like sun-planet system which the model imitates However, there are some fundamental differences between the two situations While the planetary system is held by gravitational force, the nucleus-electron system being charged objects, interact by Coulomb’s Law of force
9
2297-2300
4 BOHR MODEL OF THE HYDROGEN ATOM The model of the atom proposed by Rutherford assumes that the atom, consisting of a central nucleus and revolving electron is stable much like sun-planet system which the model imitates However, there are some fundamental differences between the two situations While the planetary system is held by gravitational force, the nucleus-electron system being charged objects, interact by Coulomb’s Law of force We know that an object which moves in a circle is being constantly accelerated – the acceleration being centripetal in nature
9
2298-2301
However, there are some fundamental differences between the two situations While the planetary system is held by gravitational force, the nucleus-electron system being charged objects, interact by Coulomb’s Law of force We know that an object which moves in a circle is being constantly accelerated – the acceleration being centripetal in nature According to classical electromagnetic theory, an accelerating charged particle emits radiation in the form of electromagnetic waves
9
2299-2302
While the planetary system is held by gravitational force, the nucleus-electron system being charged objects, interact by Coulomb’s Law of force We know that an object which moves in a circle is being constantly accelerated – the acceleration being centripetal in nature According to classical electromagnetic theory, an accelerating charged particle emits radiation in the form of electromagnetic waves The energy of an accelerating electron should therefore, continuously decrease
9
2300-2303
We know that an object which moves in a circle is being constantly accelerated – the acceleration being centripetal in nature According to classical electromagnetic theory, an accelerating charged particle emits radiation in the form of electromagnetic waves The energy of an accelerating electron should therefore, continuously decrease The electron would spiral inward and eventually fall into the nucleus (Fig
9
2301-2304
According to classical electromagnetic theory, an accelerating charged particle emits radiation in the form of electromagnetic waves The energy of an accelerating electron should therefore, continuously decrease The electron would spiral inward and eventually fall into the nucleus (Fig 12
9
2302-2305
The energy of an accelerating electron should therefore, continuously decrease The electron would spiral inward and eventually fall into the nucleus (Fig 12 6)
9
2303-2306
The electron would spiral inward and eventually fall into the nucleus (Fig 12 6) Thus, such an atom can not be stable
9
2304-2307
12 6) Thus, such an atom can not be stable Further, according to the classical electromagnetic theory, the frequency of the electromagnetic waves emitted by the revolving electrons is equal to the frequency of revolution
9
2305-2308
6) Thus, such an atom can not be stable Further, according to the classical electromagnetic theory, the frequency of the electromagnetic waves emitted by the revolving electrons is equal to the frequency of revolution As the electrons spiral inwards, their angular velocities and hence their frequencies would change continuously, and so will the frequency of the light emitted
9
2306-2309
Thus, such an atom can not be stable Further, according to the classical electromagnetic theory, the frequency of the electromagnetic waves emitted by the revolving electrons is equal to the frequency of revolution As the electrons spiral inwards, their angular velocities and hence their frequencies would change continuously, and so will the frequency of the light emitted Thus, they would emit a continuous spectrum, in contradiction to the line spectrum actually observed
9
2307-2310
Further, according to the classical electromagnetic theory, the frequency of the electromagnetic waves emitted by the revolving electrons is equal to the frequency of revolution As the electrons spiral inwards, their angular velocities and hence their frequencies would change continuously, and so will the frequency of the light emitted Thus, they would emit a continuous spectrum, in contradiction to the line spectrum actually observed Clearly Rutherford model tells only a part of the story implying that the classical ideas are not sufficient to explain the atomic structure
9
2308-2311
As the electrons spiral inwards, their angular velocities and hence their frequencies would change continuously, and so will the frequency of the light emitted Thus, they would emit a continuous spectrum, in contradiction to the line spectrum actually observed Clearly Rutherford model tells only a part of the story implying that the classical ideas are not sufficient to explain the atomic structure FIGURE 12
9
2309-2312
Thus, they would emit a continuous spectrum, in contradiction to the line spectrum actually observed Clearly Rutherford model tells only a part of the story implying that the classical ideas are not sufficient to explain the atomic structure FIGURE 12 5 Emission lines in the spectrum of hydrogen
9
2310-2313
Clearly Rutherford model tells only a part of the story implying that the classical ideas are not sufficient to explain the atomic structure FIGURE 12 5 Emission lines in the spectrum of hydrogen Niels Henrik David Bohr (1885 – 1962) Danish physicist who explained the spectrum of hydrogen atom based on quantum ideas
9
2311-2314
FIGURE 12 5 Emission lines in the spectrum of hydrogen Niels Henrik David Bohr (1885 – 1962) Danish physicist who explained the spectrum of hydrogen atom based on quantum ideas He gave a theory of nuclear fission based on the liquid- drop model of nucleus
9
2312-2315
5 Emission lines in the spectrum of hydrogen Niels Henrik David Bohr (1885 – 1962) Danish physicist who explained the spectrum of hydrogen atom based on quantum ideas He gave a theory of nuclear fission based on the liquid- drop model of nucleus Bohr contributed to the clarification of conceptual problems in quantum mechanics, in particular by proposing the comple- mentary principle
9
2313-2316
Niels Henrik David Bohr (1885 – 1962) Danish physicist who explained the spectrum of hydrogen atom based on quantum ideas He gave a theory of nuclear fission based on the liquid- drop model of nucleus Bohr contributed to the clarification of conceptual problems in quantum mechanics, in particular by proposing the comple- mentary principle NIELS HENRIK DAVID BOHR (1885 – 1962) Rationalised 2023-24 Physics 298 EXAMPLE 12
9
2314-2317
He gave a theory of nuclear fission based on the liquid- drop model of nucleus Bohr contributed to the clarification of conceptual problems in quantum mechanics, in particular by proposing the comple- mentary principle NIELS HENRIK DAVID BOHR (1885 – 1962) Rationalised 2023-24 Physics 298 EXAMPLE 12 4 FIGURE 12
9
2315-2318
Bohr contributed to the clarification of conceptual problems in quantum mechanics, in particular by proposing the comple- mentary principle NIELS HENRIK DAVID BOHR (1885 – 1962) Rationalised 2023-24 Physics 298 EXAMPLE 12 4 FIGURE 12 6 An accelerated atomic electron must spiral into the nucleus as it loses energy
9
2316-2319
NIELS HENRIK DAVID BOHR (1885 – 1962) Rationalised 2023-24 Physics 298 EXAMPLE 12 4 FIGURE 12 6 An accelerated atomic electron must spiral into the nucleus as it loses energy Example 12
9
2317-2320
4 FIGURE 12 6 An accelerated atomic electron must spiral into the nucleus as it loses energy Example 12 4 According to the classical electromagnetic theory, calculate the initial frequency of the light emitted by the electron revolving around a proton in hydrogen atom
9
2318-2321
6 An accelerated atomic electron must spiral into the nucleus as it loses energy Example 12 4 According to the classical electromagnetic theory, calculate the initial frequency of the light emitted by the electron revolving around a proton in hydrogen atom Solution From Example 12
9
2319-2322
Example 12 4 According to the classical electromagnetic theory, calculate the initial frequency of the light emitted by the electron revolving around a proton in hydrogen atom Solution From Example 12 3 we know that velocity of electron moving around a proton in hydrogen atom in an orbit of radius 5
9
2320-2323
4 According to the classical electromagnetic theory, calculate the initial frequency of the light emitted by the electron revolving around a proton in hydrogen atom Solution From Example 12 3 we know that velocity of electron moving around a proton in hydrogen atom in an orbit of radius 5 3 × 10–11 m is 2
9
2321-2324
Solution From Example 12 3 we know that velocity of electron moving around a proton in hydrogen atom in an orbit of radius 5 3 × 10–11 m is 2 2 × 10–6 m/s
9
2322-2325
3 we know that velocity of electron moving around a proton in hydrogen atom in an orbit of radius 5 3 × 10–11 m is 2 2 × 10–6 m/s Thus, the frequency of the electron moving around the proton is ( ) 6 1 11 2
9
2323-2326
3 × 10–11 m is 2 2 × 10–6 m/s Thus, the frequency of the electron moving around the proton is ( ) 6 1 11 2 2 10 m s 2 2 5
9
2324-2327
2 × 10–6 m/s Thus, the frequency of the electron moving around the proton is ( ) 6 1 11 2 2 10 m s 2 2 5 3 10 m v r ν − − × = = π π × » 6
9
2325-2328
Thus, the frequency of the electron moving around the proton is ( ) 6 1 11 2 2 10 m s 2 2 5 3 10 m v r ν − − × = = π π × » 6 6 × 1015 Hz
9
2326-2329
2 10 m s 2 2 5 3 10 m v r ν − − × = = π π × » 6 6 × 1015 Hz According to the classical electromagnetic theory we know that the frequency of the electromagnetic waves emitted by the revolving electrons is equal to the frequency of its revolution around the nucleus
9
2327-2330
3 10 m v r ν − − × = = π π × » 6 6 × 1015 Hz According to the classical electromagnetic theory we know that the frequency of the electromagnetic waves emitted by the revolving electrons is equal to the frequency of its revolution around the nucleus Thus the initial frequency of the light emitted is 6
9
2328-2331
6 × 1015 Hz According to the classical electromagnetic theory we know that the frequency of the electromagnetic waves emitted by the revolving electrons is equal to the frequency of its revolution around the nucleus Thus the initial frequency of the light emitted is 6 6 × 1015 Hz
9
2329-2332
According to the classical electromagnetic theory we know that the frequency of the electromagnetic waves emitted by the revolving electrons is equal to the frequency of its revolution around the nucleus Thus the initial frequency of the light emitted is 6 6 × 1015 Hz It was Niels Bohr (1885 – 1962) who made certain modifications in this model by adding the ideas of the newly developing quantum hypothesis
9
2330-2333
Thus the initial frequency of the light emitted is 6 6 × 1015 Hz It was Niels Bohr (1885 – 1962) who made certain modifications in this model by adding the ideas of the newly developing quantum hypothesis Niels Bohr studied in Rutherford’s laboratory for several months in 1912 and he was convinced about the validity of Rutherford nuclear model
9
2331-2334
6 × 1015 Hz It was Niels Bohr (1885 – 1962) who made certain modifications in this model by adding the ideas of the newly developing quantum hypothesis Niels Bohr studied in Rutherford’s laboratory for several months in 1912 and he was convinced about the validity of Rutherford nuclear model Faced with the dilemma as discussed above, Bohr, in 1913, concluded that in spite of the success of electromagnetic theory in explaining large-scale phenomena, it could not be applied to the processes at the atomic scale
9
2332-2335
It was Niels Bohr (1885 – 1962) who made certain modifications in this model by adding the ideas of the newly developing quantum hypothesis Niels Bohr studied in Rutherford’s laboratory for several months in 1912 and he was convinced about the validity of Rutherford nuclear model Faced with the dilemma as discussed above, Bohr, in 1913, concluded that in spite of the success of electromagnetic theory in explaining large-scale phenomena, it could not be applied to the processes at the atomic scale It became clear that a fairly radical departure from the established principles of classical mechanics and electromagnetism would be needed to understand the structure of atoms and the relation of atomic structure to atomic spectra
9
2333-2336
Niels Bohr studied in Rutherford’s laboratory for several months in 1912 and he was convinced about the validity of Rutherford nuclear model Faced with the dilemma as discussed above, Bohr, in 1913, concluded that in spite of the success of electromagnetic theory in explaining large-scale phenomena, it could not be applied to the processes at the atomic scale It became clear that a fairly radical departure from the established principles of classical mechanics and electromagnetism would be needed to understand the structure of atoms and the relation of atomic structure to atomic spectra Bohr combined classical and early quantum concepts and gave his theory in the form of three postulates
9
2334-2337
Faced with the dilemma as discussed above, Bohr, in 1913, concluded that in spite of the success of electromagnetic theory in explaining large-scale phenomena, it could not be applied to the processes at the atomic scale It became clear that a fairly radical departure from the established principles of classical mechanics and electromagnetism would be needed to understand the structure of atoms and the relation of atomic structure to atomic spectra Bohr combined classical and early quantum concepts and gave his theory in the form of three postulates These are : (i) Bohr’s first postulate was that an electron in an atom could revolve in certain stable orbits without the emission of radiant energy, contrary to the predictions of electromagnetic theory
9
2335-2338
It became clear that a fairly radical departure from the established principles of classical mechanics and electromagnetism would be needed to understand the structure of atoms and the relation of atomic structure to atomic spectra Bohr combined classical and early quantum concepts and gave his theory in the form of three postulates These are : (i) Bohr’s first postulate was that an electron in an atom could revolve in certain stable orbits without the emission of radiant energy, contrary to the predictions of electromagnetic theory According to this postulate, each atom has certain definite stable states in which it Rationalised 2023-24 299 Atoms can exist, and each possible state has definite total energy
9
2336-2339
Bohr combined classical and early quantum concepts and gave his theory in the form of three postulates These are : (i) Bohr’s first postulate was that an electron in an atom could revolve in certain stable orbits without the emission of radiant energy, contrary to the predictions of electromagnetic theory According to this postulate, each atom has certain definite stable states in which it Rationalised 2023-24 299 Atoms can exist, and each possible state has definite total energy These are called the stationary states of the atom
9
2337-2340
These are : (i) Bohr’s first postulate was that an electron in an atom could revolve in certain stable orbits without the emission of radiant energy, contrary to the predictions of electromagnetic theory According to this postulate, each atom has certain definite stable states in which it Rationalised 2023-24 299 Atoms can exist, and each possible state has definite total energy These are called the stationary states of the atom (ii) Bohr’s second postulate defines these stable orbits
9
2338-2341
According to this postulate, each atom has certain definite stable states in which it Rationalised 2023-24 299 Atoms can exist, and each possible state has definite total energy These are called the stationary states of the atom (ii) Bohr’s second postulate defines these stable orbits This postulate states that the electron revolves around the nucleus only in those orbits for which the angular momentum is some integral multiple of h/2p where h is the Planck’s constant (= 6