TOPIC: NIELS BOHR’S ATOMIC MODEL1.According to the Bohr’s orbit model, electrons may be present at any of the allowed orbits whose energy is defined by the expression: En = -2.179 x 10-18 J(Z2/n2), where Z is the atomic number or nuclear charge, and n = 1, 2, 3, ..is called the quantum number. For hydrogen atom that has Z = 1, the energy of the first four orbits are given below: ——————————————————————————Quantum #Energy values_________________n = 1-2.18 x 10-18 J(lowest energy level or “ground state”)n = 2-5.45 x 10-19 J(first excited state)n = 3-2.42 x 10-19 J(second excited state)n = 4-1.36 x 10-19 J(third excited state)——————————————————————————(Speed of light, c = 2.998 x 108 m/s;h = 6.626 x 10-34 J.s.;1 nm = 10-9 m;1 m = 109 nm) (a) Why are the energy values negative?(b) An electron in hydrogen atom jumps from the first orbit (n = 1) to the 4th orbit (n = 4). What is the energy change (E) for the electron? Does the electron gain or lose energy? Explain. What are the frequency () and wavelength () of light that would provide just enough energy for the electron to make this jump? In what spectral region is this light found, uv, visible, or infra-red region?(c) The same electron then jumps from the 4th orbit to the second orbit (n = 2). What is the energy change (E) for the electron in this jump? Does the electron gain or lose energy? Explain. What are the frequency () and wavelength () of light emitted from this energy change? In what spectral region is this light emitted, uv, visible, or infra-red region?
Emmanuel120 , 6 Years ago
Grade 12th pass
