Simplified. The absorption spectra of ions have been used to identify the presence of the elements in the atmospheres of the sun and other stars. What is the energy of a photon (in J) that is absorbed by He+ ions, when an electron is excited from the Bohr orbit with n = 1 to the n = 4 state? The energy of an electron in the nth level is

Respuesta :

Answer : The energy of a photon absorbed by [tex]He^+[/tex] ions is [tex]8.18\times 10^{-18}J[/tex]

Explanation :

The energy of an electron in the nth level is,

[tex]E_n=-\frac{BZ^2}{n^2}[/tex]

where,

[tex]E_n[/tex] = energy of an electron in the nth level

B = constant = [tex]2.18\times 10^{-18}J[/tex]

n = number of energy level

Z = charge on nucleus or number of protons

First we have to calculate the energy of an electron for n = 1 level.

[tex]E_1=-\frac{BZ^2}{1^2}[/tex]

Z = charge on nucleus or number of protons for helium atom = 2

[tex]E_1=-\frac{(2.18\times 10^{-18})\times (2)^2}{1^2}[/tex]

[tex]E_1=-8.72\times 10^{-18}J[/tex]

Now we have to calculate the energy of an electron for n = 4 level.

[tex]E_4=-\frac{BZ^2}{4^2}[/tex]

Z = charge on nucleus or number of protons for helium atom = 2

[tex]E_4=-\frac{(2.18\times 10^{-18})\times (2)^2}{4^2}[/tex]

[tex]E_4=-5.45\times 10^{-19}J[/tex]

Now we have to calculate the energy of a photon that is absorbed by [tex]He^+[/tex] ions.

[tex]E=E_4-E_1[/tex]

[tex]E=(-5.45\times 10^{-19})-(-8.72\times 10^{-18})[/tex]

[tex]E=8.18\times 10^{-18}J[/tex]

Therefore, the energy of a photon absorbed by [tex]He^+[/tex] ions is [tex]8.18\times 10^{-18}J[/tex]