11th Class Chemistry Structure of Atom / परमाणु संरचना

  • question_answer 11)
    What are the frequency and wavelength of a photon emitted during a transition from n = 5 to the n = 2 state in the hydrogen atom?

    Answer:

    Information shadow: In this problem, energy levels of transition and the name of element are given. \[{{n}_{2}}=5\] (higher energy level) ...(i) \[{{n}_{1}}=2\](lower energy level) ...(ii) Atomic number of the element (hydrogen), i.e., Z = 1 Problem solving strategy: When transition of electrons takes place from higher level to lower level, the energy is released in the form of electromagnetic radiation. The wavelength of emitted radiation can be calculated using following Rydberg equation \[\frac{1}{\lambda }=R{{Z}^{2}}\left[ \frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}} \right]\] (i) where R = Rydberg's constant ...(iv) \[=109677.76c{{m}^{-1}}\] Working it out: Substituting the values of \[{{n}_{1}},{{n}_{2}}\], R and Z in equation (iii), we get \[\frac{1}{\lambda }=109677.76\times {{1}^{2}}\left[ \frac{1}{{{2}^{2}}}-\frac{1}{{{5}^{2}}} \right]\] \[\lambda =4.34\times {{10}^{-5}}cm\] \[\lambda =4.34\times {{10}^{-9}}m\] \[\lambda =4.34nm\] Frequency \[v=\frac{c}{\lambda }=\frac{3\times {{10}^{8}}}{434\times {{10}^{-9}}}=6.91\times {{10}^{14}}Hz\]


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