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_ ———_, , ry Key Terms, Definitions & Formulas, , 22 Handbook of Chemist :, G, + those orbits for which the ang,, 2, The electrons can move only ~ ite CP s ngula we, +e i » yple 1,6., momentum 18 a0 integral mulip on _, mor _nh (n =1, 2,3. in an @, 2n ), where, m = mass of electron; v = velocity of electron;, py =radius of orbit, , From |, , hich electrons are present, , n =number of orbit in W, nly when an electron jumps from vor'K, , 3. Energy is emitted or absorbed 0 ¢, higher energy level to lower energy level and vice-versa. ‘, he :, AE = E, - By = hv = M, : N, , 4. The most stable state of an atom is its ground state or normal, state. Li mil, From Bohr’s model, energy, velocity and radius of an electron in , nth Bohr orbit are, , Z, , (i) Velocity of an electron in nth Bohr orbit, , (v,) = 2.165 x 10° 2 sais, mn, , , , , , , , , , , (ii) Radius of nth Bohr orbit, (74) = 0.53 10° a m = 0.53 5 A, , 2, , Gi) E, =-2.178x 107° 4 J/atom, n, , 2, ~~ 1312 4 kd mol, n, , 2, =- 13.62, eV/atom, n, , AE =-2.178x 10" ( a | Z? Jlatom, 2 2, ny Ng, , where, n = number of shell; Z = atomic number, , As we go away from the nucleus, the energy levels come clos, i.e. with the increase in the value of n, the difference of ener, , between successive orbits decreases., Thus, E, —E, > E, - E, > Ey - Ey > E; — Ey ete.

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Handbook of Chemistry Key Terms, Definitions & Formulas 23, , Sommerfeld Extension to Bohr’s Model, According to this theory, the angular momentum of revolving electron, in an elliptical orbit is an integral multiple of rm Le., , kh, mur =>, 2s, , From Bohr model, mur = “, , For K shell, n =1,%=1 Circular shape, L shell, n = 2, k=1,2 Circular, M shell, n =3, k= 1,2, 3 Elliptical, N shell, n-4,4=1,2,3,4 Elliptical, , Limitations of Bohr’s Theory, , 1. It is unable to explain the spectrum of atom other than hydrogen, like doublets or multiclectron atoms,, , 2, It could not explain the ability of atom to form molecules by, chemical bonds. Hence, it could not predict the shape of, molecules., , 3. It is not in accordance with the Heisenberg uncertainty principle, and could not explain the concept of dual character of matter., , 4. It is unable to explain the splitting of spectral lines in the, , presence of magnetic field (Zeeman effect) and clectric field, (Stark effect)., , de-Broglie Principle (Dua! Nature), , de-Broglie explains the dual nature of electron i.e. both 4, pore ane ie. particle as well, , sate i) h =i, =, oF , [p= mv (momentum)), where, . « wavelength; v « velocity of particle; m = mass of particle, he, Jam*KE, , KE = kinetic energy.