Question

Please answer and explain

6. It takes 7.21x10-19J of energy to remove an electron from an atom of iron. Which of the following would be able to do it? A. A photon with wavelength 276 nm B. A photon with frequency 1.1x1015 Hz C. Ten photons of frequency 1.1x1014 Hz each D. A and B E. All of the above

7. A particle has a velocity that is 90. % of the speed of light. If it is a wave with λ = 1.5x10-15m, what is its mass? A. 1.6 x 10-27 kg B. 1.6 x 10-15 kg C. 1.78 x 10-27 g D. 1.78 x 10-27 kg

8. The particle in questions 7 could be… A. A proton B. An electron C. A photon D. None of the above

9. Which of the following sets of quantum numbers is forbidden? A. n = 3, l = 3, ml = –3 B. n = 3, l = 2, ml = –3 C. n = 3, l = 1, ml = 0 D. n = 3, l = 2, ml = 0

Answer 1

E = 7.21*10^-19 J/electron

a) photon at WL = 276 nm

calculate energy...

WL = h c / E

h = Planck Constant = 6.626*10^-34 J s

c = speed of particle (i.e. light) = 3*10^8 m/s

E = energy per particle J/photon

E = hc/WL = (6.626*10^-34)(3*10^8) / (276 *10^-9) = 7.202*10^-19

Energy is not enough...

b) photon at v = 1.1*10^15 Hz

E = hv

so..

E = (6.626*10^-34)(1.1*10^15) = 7.28*10^-19 J

this will do!

c) 10 photons of v = 1.1*10^14

Etotal = nphotons*Ephoton = 10*((6.626*10^-34)(1.1*10^14) = 7.288*10^-19 J... this will also do!

8

must be electron... since it has the mass requirement for moving across the atom

Q9

A. n = 3, l = 3, ml = –3 --> impossible, since l = n-1 = 3-1 = 2; value of 3 is not possible

B. n = 3, l = 2, ml = –3 --> impossible, since ml = +/- l; since l = 2, can't have 3 value

C. n = 3, l = 1, ml = 0

D. n = 3, l = 2, ml = 0