TTU General Chemistry

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Chem 111 - Quiz 5B - Fall, 1997
Chapter V: The Structure of Atoms

Physical constants: h = 6.626 x 10-34 Joule-sec; c = 3.00 x 108 m/s; mass of electron = 9.1 x 10-31 kg

1. Consider the following historical statements:

I. The Millikan "oil drop" experiment was able to determine the charge of an electron.
II. Rutherford's "gold foil experiment" established the nuclear atom concept.
III. Thomson determined the charge to mass ratio of electrons in his cathode ray tube experiments.

a) I and II are correct but III is false.
b) II and III are correct but I is false.
c) I and III are correct but II is false.
d) All are correct.

2. Identify the INCORRECT statement regarding the gold foil experiment:

a) A few particles rebounded as if hitting very dense positive charges in the foil.
b) Most particles bounced back from the gold foil.
c) Most particles passed through the foil as if through empty space.
d) The gold foil was bombarded with positively charged alpha particles, having a mass four times that of a proton.

3. Identify the INCORRECT statement below:

a) The mass number of an atom is the number of neutrons plus protons in the atom.
b) The neutron has nearly the same mass as the proton but zero charge.
c) Two elements differ from one another by having a differing mass number.
d) Atomic number is the number of protons in the nucleus of an atom.
e) The mass of the electrons is a small fraction of the total mass of any atom.

4. The element Fluorine has only one really stable isotope. What is the composition of its nucleus?

a) 19 protons
b) 9 protons and 19 neutrons
c) 9 protons and 10 neutrons
d) 10 protons and 9 neutrons

5. A neutral atom of the 235U isotope has how many protons, neutrons, and electrons?

a) 92 p, 143 n, 92 e
b) 235 p, 235 n, 235 e
c) 92 p, 92 n, 92 e
d) 92 p, 235 n, 92 e

6. What is the wavelength in meters of microwave radiation, having a typical frequency of 3 x 109 Hz?

a) 9 x 10-17 m
b) 9 x 1017 m
c) 10 m
d) 0.1 m

7. What is the energy in Joules of a mole of photons of microwave light having a frequency typical of microwave? (frequency = 3.0 x 109 Hz). (A Joule is enough energy to raise the temperature of 1 gram of water about a quarter of a degree Celsius.)

a) 1.2 x 1023 J
b) 1.98 x 10-24 J
c) 1.2 J
d) 1.98 x 10-34 J

8. Rank the following types of radiation from highest energy to lowest:

ultraviolet / visible / xray / microwave / infrared

a) xray, ultraviolet, microwave, infrared, visible
b) ultraviolet, xray, visible, infrared, microwave
c) infrared, microwave, ultraviolet, visible, xray
d) xray, ultraviolet, infrared, visible, microwave
e) xray, ultraviolet, visible, infrared, microwave

9. An excited Hydrogen atom in the n=3 energy level decays to the n=2 energy level and emits a photon of light. If the energies of these two levels are separated by 3.029 x 10-19 J, what will be the wavelength of the light emitted in nanometers?

a) 656 nm
b) 484 nm
c) 1073 nm
d) 1.07 x 10-19 nm
e) 3.3 x 10-10 nm

10. According to the deBroglie equation, the characteristic wavelength of an electron moving around an atomic nucleus will be:

a) about the size of the nucleus.
b) about the same size as the atom.
c) large compared to the atomic scale.
d) immeasurably small compared to any dimensions we care about.

11. Which is the following is an INCORRECT electron configuration?

a) Ti = [Ar]4s23d2
b) S = [Ne]2s22p4
c) Li = 1s22s1
d) C = [He]2s22p2

12. Identify the INCORRECTstatement below:

a) The total number of electrons required to fill the n=1 level is 2.
b) The total number of electrons that can have n=2 in a many-electron atom is 8.
c) The total number of electrons that can occupy an atomic orbital is 2.
d) The total number of electrons that can "fit" in the 3d sublevel is 5.

13. The statement that no two electrons can have the same set of four quantum numbers in any atom is a consequence of:

a) The Aufbau Principle.
b) The Heisenberg Uncertainty Principle.
c) The Pauli Exclusion Principle.
d) Hund's Rule.

14. Which of the following full notations for the electron state is consistent with the last electron added in forming the electron configuration of Scandium (Sc)?

a) (3, 2, 1, +1/2)
b) (4, 0, 0, +1/2)
c) (4, 2, 0, +1/2)
d) (4, 2, 1, +1/2)

15. Fill in the blank: The l quantum number tells which sublevel the electron is in and most directly specifies the _______ of the atomic orbital.

a) orientation
b) size
c) energy
d) shape

KEY

1.d 2.b 3.c 4.c 5.a 6.d 7.c 8.e 9.a 10.b 11.b 12.d 13.c 14.a 15.d