Chapter 18: The Structure of the Atom

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Chapter 18: The Structure of the Atom

1. For most elements, an atom has A. no neutrons in the nucleus.

B. more protons than electrons.

C. less neutrons than electrons.

D. just as many electrons as protons.

E. just as many neutrons as electrons.

Answer: D

2. A true statement about atoms is that they A. can emit radiation only at specific frequencies.

B. all have the same number of electrons.

C. can emit radiation at any frequency.

D. can emit radiation at frequencies only within the visible spectrum.

Answer: A

3. The atomic number of an atom is the number of A. electrons in the nucleus.

B. protons in the nucleus.

C. sum of protons and electrons in the atom.

D. neutrons in the nucleus.

E. sum of protons and neutrons in the atom.

Answer: B

4. The maximum number of electrons allowed in the n = 1 shell of sodium is A. 8.

B. 6.

C. 4.

D. 2.

E. unlimited.

Answer: D

5. The periodic table is a systematic arrangement of A. all known molecules.

B. those materials that are conductors.

C. the non-radioactive elements.

D. all known elements.

Answer: D

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6. The principal characteristic that distinguishes one element from another is the A. number of protons is the nucleus.

B. number of neutrons in the nucleus.

C. combined number of protons and neutrons in the nucleus.

D. number of variations in the electron configuration.

E. size of the atom.

Answer: A

7. A block of granite is mostly empty space because the atoms making up the granite are A. in perpetual motion.

B. themselves mostly empty space.

C. not as close together as they should be.

D. held together by electrical forces.

Answer: B

8. When an atom has an electron removed, then its net charge is A. unchanged.

B. negative.

C. positive.

D. … it is impossible to remove an electron from an atom.

Answer: C

9. When the electron loses its charge, then it A. becomes a neutron..

B. is still an electron but doesn’t have its charge.

C. is now repelled by protons.

D. becomes a photon.

E. … it is impossible to remove a charge from an electron.

Answer: E

10. Which is the smallest entity in the following list?

A. Proton B. Nucleus C. Atom D. Molecule Answer: A

11. The Bohr theory of the atom made the following BOLD assumption:

A. The electrons in some orbits are paired so as to become stable.

B. Electrons in certain orbits do not radiate electromagnetic waves despite being centripetally accelerated.

C. The stable orbits are maximally occupied with electrons.

D. All atoms contain “special” electrons that do not radiate their energy.

Answer: B

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12. The force that holds all atoms together is A. magnetic.

B. gravitational.

C. electrical.

D. nuclear.

Answer: C 13. A pencil has

A. no electric charges in it.

B. more nuclei than protons.

C. an equal number of electrons and protons.

D. a net positive charge.

Answer: C

14. A true statement about atoms is that they A. consist mostly of empty space.

B. all have the same number of electrons.

C. are basically unstable.

D. are big enough to be seen by the eye.

Answer: A

15. A true statement about our “model” of light is that A. all experiments have shown that light is a wave.

B. light sometimes behaves as particles, sometimes as waves.

C. light is a standing wave of electrical energy.

D. there is no evidence of any inaccuracy of the Bohr model of atom.

Answer: B

16. One of the fundamental ideas in the development of Quantum Mechanics was that A. no two particles can have the same energy.

B. all particles are formed by the interaction of electromagnetic waves.

C. electrons and protons are the only particles with mass.

D. all particles have wave properties.

Answer: D

17. What is “uncertain” in the Heisenberg Uncertainty principle?

A. The value of the particle’s position when the particle’s momentum is known precisely.

B. The time period of the wave describing the particle.

C. The energy of the particle when it has wave properties.

D. The exact number of protons in the nucleus.

E. The value of the Planck’s constant.

Answer: A

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18. Quantum mechanics has accurately described the regularities of the periodic table by assigning “quantum” numbers to predict the allowed energy levels. The true statement about quantum numbers is that

A. there are never more than 8 different sets of quantum numbers in an atom.

B. no electrons in the world can ever have the same set of quantum numbers.

C. no two electrons in the same atom can have the same set of quantum numbers.

D. they describe the position and charge of the electrons in the atoms.

Answer: C

19. The scientist whose Law of Definite Proportions provided strong evidence for the atomic theory is

A. Faraday.

B. Bohr.

C. Dalton.

D. Lavoisier.

E. Rutherford.

Answer: C

20. Cathode rays produced in a gas discharge tube are A. x-rays.

B. electrons.

C. protons.

D. alpha particles.

E. gamma rays.

Answer: B

21. Natural radioactive rays that will not be deflected by a magnetic field are A. alpha rays.

B. beta rays.

C. gamma rays.

Answer: C

22. In scattering of fast alpha particles by a thin foil of gold Rutherford and his collaborators observed

A. many alpha particles scattered through large angles.

B. a very few alpha particles scattered through large angles with most undergoing very little scattering.

C. alpha particles only scattered through small angles.

Answer: B

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23. The idea that light could be emitted only in discrete chunks or quanta instead of in continuous amounts was first put forth to explain which of the following phenomena?

A. the spectrum of atomic hydrogen B. blackbody radiation

C. x-rays D. cathode rays E. radioactive decay Answer: B

24. The transition in atomic hydrogen that gives the longest wavelength in the visible spectrum is

A. n = 2 to n = 1.

B. n = 3 to n = 1.

C. n = 4 to n = 1.

D. n = 3 to n = 2.

E. n= 4 to n = 2.

Answer: D

25. A series of transitions in atomic hydrogen that produce emissions all in the ultraviolet portion of the spectrum are those ending in the level

A. n = 1.

B. n = 2.

C. n = 3.

D. n = 4.

E. n = 5.

Answer: A

26. If h = Planck’s constant, the frequency of light emitted when an atom makes a transition is equal to

A. the energy of the initial atomic state divided by h.

B. the energy of the final atomic state divided by h.

C. the difference in the energies of the initial and final atomic states divided by h.

D. the ionization energy of the atom divided by h.

E. the frequency of revolution of the electron in its lowest energy orbit.

Answer: C

27. If h = Planck’s constant, the de Broglie wavelength of a particle of linear momentum p and kinetic energy KE is

A. h/p.

B. p/h.

C. KE/h.

D. h

^.

p.

E. h/KE.

Answer: A

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28. Which of the following individuals did not directly contribute to quantum theory?

A. Planck B. Heisenberg C. Roentgen D. Schrödinger E. Einstein Answer: C

29. The helium atom has one more electron than hydrogen. The chemical properties differ because helium

A. is more reactive since it has two electrons that can form chemical bonds.

B. is much less reactive since its two electrons form a stable closed shell.

C. and hydrogen are equally reactive since chemical bonding has nothing to do with the number of electrons.

D. has neutrons in the nucleus.

Answer: B

30. Classical physics applied to the Bohr model of the hydrogen atom would predict that light could be emitted continuously, rather than in discrete chunks of energy. Transitions between what kinds of energy levels would come close to the classical viewpoint?

A. Only levels having small quantum numbers.

B. Only when at least one of the levels has a very large quantum number.

C. Only levels of moderate quantum numbers.

D. There are no such levels.

Answer: B

31. Radiation from naturally radioactive uranium having the largest mass are _____________

rays.

Answer: alpha

32. The energy of a photon is calculated from the product of the constant h times the ________________.

Answer: frequency

33. In the Bohr model of the hydrogen atom the non-radiating orbits are determined by quantizing the _______________(physical quantity).

Answer: angular momentum

34. The Bohr condition for determining the stable orbits in hydrogen can be explained in terms of ___________________ for the electron (more than one word).

Answer: standing waves

35. The Balmer series of spectral lines corresponds to transitions ending in a state of quantum number ____________.

Answer: 2

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36. The electron was discovered by (one name) in his study of ____ (two words).

Answer: Thomson, cathode rays

37. X-rays are ___ waves of _ wavelength.

Answer: electromagnetic, short

38. According to Heisenberg’s principle, if one attempts to make a precise measurement of the linear momentum of a particle, he/she will get a large uncertainty in the determination of the ________ of the particle.

Answer: position