Physics 30: Chapter 7 Exam – Atomic Structure
Name: ______Date: ______Mark: ____/30
Numeric Response. Place your answers to the numeric response questions, with units, in the blanks at the side of the page. (1 mark each)
1. / Calculate the charge-to-mass ratio of an electron.2. / A stream of protons enters a 7000 N/C electric field and a 6.0 mT magnetic field in a CRT. The beam is not deflected as it passes through the two perpendicular fields. Determine the speed of the protons in the undeflected beam.
3. / Determine the deBroglie wavelength of a proton moving at 6.50 x 107 m/s.
4. / The possible energies of an electron within an atom are given in the energy level diagram as shown to the right. Determine the wavelength of a photon released as an electron makes a transition from level D to B.
Written Response. Show all your work. Clearly identify your final answer(s) rounded off to the proper number of significant digits.
1. Mercury gas is used in fluorescent lights and many street lamps. Some of the possible transitions for an electron in a mercury atom are given in the energy level diagram shown on the right.
A passing electron that has a kinetic energy of 6.90 eV contacts the electron within a mercury atom at ground state. Determine the
a. total number of different photons that could possibly be produced. (1 mark)
b. wavelength of the photon with the maximum energy.
(2 marks)
c. maximum possible deBroglie wavelength of the passing electron after the collision. (3 marks)
Multiple Choice. Select the best answer and mark it clearly on your Scantron. (1 mark each)
1. Thomson’s work with cathode ray tubes suggested that an atom contained
a. / a nucleusb. / protons
c. / neutrons
d. / electrons
2. A charged particle with of unknown identity is sent through a cathode ray tube. It then enters a perpendicular magnetic field of 0.30 T with a speed of 4.0 x 106 m/s and follows a circular path with a radius of 9.0 cm. The charge-to-mass ratio of this unknown particle is
a. / 6.8 x 10-7 C/kgb. / 1.5 x 106 C/kg
c. / 6.8 x 10-9 C/kg
d. / 1.5 x 108 C/kg
3. A charged particle is accelerated across a potential difference (V). It then enters a perpendicular electric field (|E|) and magnetic field (B). The force exerted by the magnetic field on the particle is equal in magnitude to the force produced by the electric field so that the particle is not deflected. The charge-to-mass ratio of the particle may be written as
a. / b. 2|E|2V B2c. / d.
4. Rutherford suggested the nuclear atom after doing ______experiments
a. / cathode rayb. / oil drop
c. / scattering
d. / blackbody
5. Rutherford’s nuclear model must be invalid because
a. / a nucleus cannot exist in close proximity to electronsb. / accelerating charges should produce EMR
c. / Thomson had proven that atoms are solid
d. / electrons are waves
6. A line-absorption spectra may be produced by
a. / placing a large potential difference across a gas filled CRTb. / shinning white light through a gas at room temperature
c. / heating a gas to a very high temperature
d. / placing a chemical into a Bunsen burner flame
7. The concepts of stationary states for electron in around a nucleus is used to explain
b. / the nucleus of an atom
c. / black body radiation
d. / atomic spectra
8. Electrons within a hydrogen atom fall from an excited state to ground state. Identify the type of spectra produced through this process.
a. / continuous spectrab. / line-emission spectra
c. / line-absorption spectra
d. / blackbody radiation
9. An electron moving with a kinetic energy of 8.00 x 10-19 J strikes an atom and rebounds with a kinetic energy of 5.00 x 10-19 J. The atom then releases a photon of light. The most likely frequency of the emitted light is
a. / 1.21 x 1015 Hzb. / 7.54 x 1014 Hz
c. / 1.96 x 1015 Hz
d. / 4.52 x 1014 Hz
Use the information below to answer questions 10 & 11.
A gas in a cathode ray tube produces the line emission spectra shown below containing four bright lines.
10. The wavelength shown having the greatest energy has an energy of
a. / 2.21 x 10-18 Jb. / 1.66 x 10-18 J
c. / 5.53 x 10-19 J
d. / 4.91 x 10-19 J
11. The bright line that is most likely in the visible spectrum is line number
a. / 1b. / 2
c. / 3
d. / 4
12. Identify the various atomic models in order of increasing sophistication.
b. / Bohr model, Rutherford Model, Thomson Model, Wave Mechanical Model
c. / Thomson Model , Bohr model, Rutherford Model, Wave Mechanical Model
d. / Thomson Model , Rutherford Model, Bohr model, Wave Mechanical Model
13. When a beam of electrons are aimed at a series of double slit in a crystal, the pattern formed on the screen behind the crystal indicates that the electrons
a. / must be particlesb. / must be waves
c. / may be waves or particles
d. / may be neither waves or particles
Use the information below to answer questions 14 – 16.
The energy level diagram for a hydrogen atom is shown to the right.
14. A photon that has an energy of 1.06 x 10-19 J is absorbed by a hydrogen atom. The most likely transition of the electron within the hydrogen atom is
a. / 4 to 3b. / 3 to 4
c. / 4 to 5
d. / 5 to 4
15. Calculate the wavelength of the photon emitted when the electron within the hydrogen atom moves from energy level 5 to energy level 2.
a. / 434 nmb. / 2.28 mm
c. / 365 nm
d. / 315 nm
16. Identify the region of the electromagnetic spectrum for the photon emitted when an electron moves from energy level 2 to energy level 1 within the hydrogen atom.
b. / infrared
c. / visible
d. / ultraviolet
17. Determine the deBroglie wavelength of an electron moving at 5.50 x 107 m/s.
a. / 8.26 x 107 mb. / 7.53 x 10-23 m
c. / 7.56 x 1010 m
d. / 1.32 x 10-11 m
18. Determine the speed of an electron which has a deBroglie wavelength of 2.10 x 10-11 m.
a. / 3.47 x 107 m/sb. / 2.47 x 107 m/s
c. / 6.54 x 1013 m/s
d. / 6.54 x 107 m/s
19. Select the phrase that best completes the sentence. The amplitude of an electron wave surrounding the nucleus of an atom may be interpreted as the ______the electron at that location.
a. / length of the wave ofb. / frequency of
c. / wavelength of
d. / probability of finding
20. Treating the electron as a wave allows for wave constructive and destructive interference effects to support the
a. / billiard ball modelb. / nuclear model
c. / Bohr energy level model
d. / wave mechanical model
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