Question

1. A hydrogen atom with its electron in the n = 5 energy level emits a photon of IR light. (i)[3 marks] Calculate the change in energy of the atom and (ii) [2 marks] Calculate the wavelength (in nm) of the photon.

Answer 1

The electron in n = 5 energy level emits a photon of IR light means the electron has deexcited to n = 3 or n = 4.

(solved question by considering n = 5 to n = 3)

(i) Energy change

  $E = h\nu = hc/\lambda = hc\bar{\nu }$
3 R=109677 care ne-3, 2-5 1 R 1096 77 cm 3' = 109677 cost [ã ) = 109677 cost [ 16/225] = 7799.253 cm hc -34 b= 6.625xJO J. Sec C = 3x10 to Can/sec E = 6.625x1834. sex xxx xx 7199.25 ca -24 = 155,010 10 Joules -19 155x10 j

Ji klavelength (x) gta 5 - R[o ho 7799.253 cast 1 1 - 7799.253 case -4 1.282 X 10 Con [Inm=100m = 107cm] X = 12820m