Question

6. The first ionization energy of Au (IE1) is 890.1 kJ/mol. Is light with a wavelength of 225 nm capable of ionizing a gold atom in the gas phase? Justify your answer with a calculation. 7. The energy of an electron in a hydrogen atom is -4.45 x 100 J. What energy level (n) does it occupy? Is there another valid energy level at -2.69 x 1020 ? If so, what is this other energy level? 8. What is the difference in energy between the two levels responsible for the emission line in the atomic spectrum of Mg at 285.2 nm? 9. An electron in the Li ion moves from the fifth to the second energy level. a) What wavelength (in nm) and frequency (in kHz) of the photon will be produced during this transition? b) What energy (in MJ) will be associated with this radiation if 0.75 mol of Li ions undergo the above transition? Express your answers for question 9 in scientific notation if applicable.

Answer 1

6)

Energy from light = hc/wavelenth = 0.08 x 10 ^ -17

IE1 = 0.148 x 10 ^ -17

IE > Light from energy, so not capable of ionizing.

7)

The quotients of energy levels in any atom is always an integer. But 4.45/2.69 = 1.65 is not. So no such energy level.

Energy level = R_e / n²

R_e = 2.18 x 10 ^ -18 J => n = 7

8)

hc/wavelenth = (Z=12)x(R_e ) / (1/n² ) - (1/(n+1)² )

Obtaining value of jumping from level 2 to level 3

9)

Apply the above formulae

But for calculation sake,

(a) The spectral line from level 2 to 5 in Hydrogen is 434nm. So in Li it'll be 434/Z = 434/3 = 144.66 nm = 1.4466 x 10^-7 m

(b) 2.18 x 10^-18 x 3 x 0.21 x 0.75 x 6.023 x 10²³ = 0.62 MJ