Download Atomic Physics

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Assessment
Atomic Physics
Teacher Notes and Answers
21 Atomic Physics
MODELS OF THE ATOM
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The Rutherford model of the atom had a
compact, massive nucleus that contained the
positive charge of the atom. The electrons
orbited this nucleus in a manner similar to
planets orbiting the sun. This model
correctly accounted for the nucleus, but
according to classical electromagnetic
theory, the orbiting electrons would radiate
energy continuously, and so could not
maintain stable orbits. Also, Rutherford’s
model provided no explanation for emission
or absorption spectra.
10. In the Bohr model of the atom, electrons
move in orbits around the nucleus, much
like planets orbit the sun. However, only
specific orbits are stable and can thus be
occupied by the electrons. When electrons
are in these orbits, they do not emit
radiation, as predicted by classical
electromagnetic theory. Radiation is emitted
when electrons move from higher-energy
levels to lower-energy levels, which
accounts for the individual lines of emission
spectra. However, Bohr’s model could not
explain why the stable orbits existed, or why
radiation was not emitted when the electrons
were in these orbits. The Bohr model also
did not predict the spectra for atoms with
more than one electron in their outermost
energy levels.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
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Section Quizzes
Name:______________________________Class:__________________ Date:__________________
Assessment
Atomic Physics
Section Quiz: Models of the Atom
Write the letter of the correct answer in the space provided.
_____ 1. What did Rutherford’s experiment demonstrate?
a. The atomic nucleus was a large spherical volume of positive charge.
b. The atomic nucleus was a small, compact region of positive charge.
c. The electrons were imbedded in the sphere of positive charge.
d. The electrons moved around the nucleus like planets orbiting the
sun.
_____ 2. What observation was not explained by the Rutherford model of the
atom?
a. the Compton shift
b. emission spectra
c. the photoelectric effect
d. blackbody radiation
_____ 3. Which of the following statements is true about an emission spectrum?
a. The wavelengths of the spectrum are the same for all elements.
b. The lines of the spectrum are equally separated.
c. It consists of dark lines in an otherwise continuous spectrum.
d. It consists of narrow bright lines.
_____ 4. What type of spectrum is observed in the light from the sun and other
stars?
a. a continuous spectrum
b. an emission spectrum
c. an absorption spectrum
d. an atomic spectrum
_____ 5. By what process does an electron in the Bohr model of the atom drop
from a higher-energy level to a lower-energy level and emit a photon?
a. line emission
b. line absorption
c. spontaneous emission
d. spontaneous absorption
_____ 6. Which of the following is a feature of the Bohr model of the atom?
a. Only specific electron orbits with given energies are stable.
b. Electrons emit radiation continuously while orbiting the nucleus.
c. Orbits of all possible energies are allowed for the atom’s electrons.
d. Electrons are located within a spherical region of positive charge.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
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Section Quizzes
Name:______________________________Class:__________________ Date:__________________
Atomic Physics continued
_____ 7. Which of the following statements correctly describes an atom’s energy
levels as they are depicted in an energy-level diagram?
a. The energy levels are separated by equal amounts.
b. The higher energy levels are separated by smaller amounts.
c. The higher energy levels are separated by greater amounts.
d. The energy levels are the same for all elements.
_____ 8. A photon with an energy of 2.86 eV is absorbed by a hydrogen atom.
Afterwards, three photons are spontaneously emitted. Which statement
correctly describes the emitted photons?
a. The emitted photons each have the same wavelengths.
b. The photons are produced by a single electron energy-level
transition.
c. The sum of the emitted photon energies equals 2.86 eV.
d. Three photons are always emitted when a 2.86 eV photon is
absorbed.
9. Describe the Rutherford model of the atom, noting its strengths and
weaknesses.
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10. Describe the Bohr model of the atom, noting its strengths and weaknesses.
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
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Section Quizzes