Bohr Model of Hydrogen Atom Practice Problems
AP Physics
Name:
Period:
49. What unusual characteristic did Bohr postulate for an electron’s orbit around the nucleus in a hydrogen
atom?
50. a) According to Bohr’s theory, when does a
hydrogen atom emit light?
b) Why does a hydrogen atom only emit particular
colors of light?
51. Explain why the Bohr theory is applicable only to the hydrogen atom or atoms that are like hydrogen [such
as singly ionized helium, doubly ionized lithium and other single electron systems]?
52. Does it take more energy to ionize (free) the electron of a hydrogen atom that is in an excited state or one
that is in the ground state? Explain.
53. Very accurate measurements of the wavelengths of light emitted by hydrogen atoms indicate that all of the
light waves emitted by real hydrogen atoms are slightly longer than predicted by the Bohr model. Consider an
excited hydrogen atom that is initially at rest and think about what happens as it emits a photon. [Hint: what
has to be conserved in any event?]
Find the energy of the electron in a hydrogen atom that is orbiting in each of the following states:
a) n = 1
c) n = 3
e) n = 8
g) n = 49
b) n = 2
d) n = 4
f) n = 10
h) n = 50
54. Find the energy required to excite the electron in a hydrogen atom for each of the following cases:
a) The electron jumps from the ground state to
c) The electron jumps from the n = 3 state to
the n = 2 state.
the n = 4 state
b) The electron jumps from the n = 2 state to
the n = 3 state
c) The electron jumps from the n = 49 state to
the n = 50 state
55. For each of the jumps in the previous problem, find the frequency and wavelength for the photon that could
force the electron to make a particular jump, then classify what part of the electromagnetic spectrum it would
fall in:
a) The electron jumps
b) The electron jumps
c) The electron jumps
d) The electron jumps
from the ground state to
from the n = 2 state to the from the n = 3 state to the from the n = 10 state to
the n = 2 state.
n = 3 state
n = 4 state
the n = 2 state
56. Find the energy needed to ionize a hydrogen atom whose electron is in each of the following states:
a) n = 1
b) n = 2
c) n = 3
d) n = 4
58. Find the frequency and wavelength of the light emitted when the electron in a hydrogen atom undergoes the
following transitions:
a) The electron drops
b) The electron drops
c) The electron drops
d) The electron drops
from the n = 3 orbit to
from the n = 4 orbit to
from the n= 5 orbit to
from the n = 10 orbit
the n = 1 orbit
the n = 2 orbit
the n = 3 orbit
to the n = 8 orbit
59. Scientists are now studying “large” atoms – atoms approaching the size of visible objects – so that they can
see if quantum affects can play into our everyday life.
a) If we wanted to “create”
b) What is the energy of
[Challenge] c) If we
a hydrogen atom that was
that excited state?
wanted a bunch of atoms to
close to the size of a speck
be able to stay in that
excited state, what is the
of dust (1 m), what
highest temperature they
excited state should the
could have so that the
atom be in?
average collision between
atoms wouldn’t ionize the
atoms?
63. The ionization energy for a hydrogen atom in the ground state is 13.6 eV.
a) Would the absorption of light with a frequency of 7.00 x
b) If so, how much kinetic energy would the
1015 Hz cause a hydrogen atom in the ground state to be ionized? emitted electron have?