A typical value for the wavelength of violet light is 400.0 nm and a typical val

Question

A typical value for the wavelength of violet light is 400.0 nm and a typical value for the wavelength of red light is 700.0 nm. Using these wavelength values, complete the following table: Show calculations for violet light here: According to the Bohr model of the hydrogen atom, the electron can be excited to only certain higher levels above the ground state (n = 1). When the excited electron returns home, it gives off energy in the form of radiation. Decide where in the electromagnetic spectrum each of the "return home" trips shown at the right will be. UV spectrum Visible spectrum IR spectrum

Explanation / Answer

2) Wavelength and frequency of light are related as

wavelength x frequency = velocity of light c

Energy of light = Planck's constant h x frequency

Using these relations

i) frequency of violet light with wqvelength 400nm is

frequency = c/ lambda

= (3.0x 108m/s ) / 400x 10-9m = 7.5 x 1014 per second or Hz

Energy of violet light = h(nu) = 6.63x 10-34Js x 7.5 x 1014/s = 4.899x 10-19J / photon

Energy of violet light per mole of photons = 4.899x 10-19 x6.023x 1023 = 294.9KJ/mol

ii) similarly for red light with wavelegth =700nm

frequency = 3.0x 108 / 7x107= 4.285x 1014Hz

energy = 6.623x 10-34 x4.285x 1014 = 2.836 x10-19J/photon

= 175.95 KJ/mol

Q3) In the Bohr's model of H- atom, the spectral lines are due to the electronic tranisitions from higher to lower levels. It is observed that electron form any higher level to ground state , n=1 ,the emitted light is observed in UV egion as LYman series, from any higher level to second, n=2 level, the emitted light in visible region, and from any higher level to n=3 in near IR region, to n=4 in IR region and above series in far IR region. Thus

transition from to to region of light observed

A n=2 to n=1 UV

B n=4 to n=2 visible

C n=3 to n=2 visible

D n=6 to n=1 UV

E n= 6 to n=3 IR

F n=6 to n=2 visible

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