Physics Test 3 Exam Questions
and Answers
Compton effect - Answer--the change in wavelength; depends on scattering angle and
not on the wavelength
De Broglie wavelength - Answer--describes wave nature of electrons
-photons have wave and particle characteristics, all forms of matter must have both
-frequency and wavelength can be determined
lambda=h/p= h/mv
f=E/h
Uncertainty Principle - Answer--if a measurement of position of a particle is made with
precision deltax and a simultaneous measurement of linear momentum is made with
precision deltap, then product of 2 uncertainties can never be smaller than h/4pi
-cant know momentum or position at the same time--> always uncertainty
(deltax)(deltap) > h/4pi
suppose we make a measurement of an electrons position. immediately afterwards, we
make a measurement of the e- momentum. immediately after measure e- position again
2nd position measurement will me ______ - Answer-different than the first
How do electrons move to different energy levels - Answer-When energy is added to an
atom, an electron can move from a lower energy level to a higher energy level. The
terms HOMO and LUMO are often used here (Highest Occupied Molecular Orbital and
Lowest Unoccupied Molecular Orbital).
electron energy change and absorption/emission - Answer-An electron in an excited
electronic state can lose energy and change to a state of lower energy. This change of
energy state, or energy level, by an electron in an atom is called an electronic transition.
The energy lost by the atom, the energy difference between the initial and final states, is
emitted as a photon.
transitions between electronic energy levels, observed either as emission or absorption
of light, occur at discrete energies or wavelengths.
emission - Answer--gas at low pressure has a voltage applied to it
-gas emits light which is characteristic of the gas
, -when analyzed with spectrometer, series of discrete bright lines is observed
-spectrum is black background with colorful lights
emission spectrum of hydrogen equation - Answer-1/lambda=Rh(1/2^2 - 2/n^2)
invert and convert to nm
Absorption - Answer--element can absorb light at specific wavelengths
-absorption spectrum can be obtained by passing a continuous radiation spectrum
through a cool vapor of the element being analyzed
-spectrum is colorful with black lines
What can we learn from spectra about an object - Answer-use to identify elements
Calculating PE - Answer-(Ke*e^2)/r
Calculating KE - Answer-1/2mv^2
Calculating total energy - Answer-E = KE + PE
Bohr's Radius - Answer-r= (n^2 (hat)^2)/mke^2
n=1 smallest radius, bohrs radius (a knott)
Principle quantum number - Answer-n
allowed values:1,2,3,4
any number
orbital quantum number - Answer-l
allowed values: n-1
number of allowed states: n
orbital magnetic quantum number - Answer-m(sube)
number of allowed states: 2l +1
allowed values: -l to +l
Pauli exclusion principle - Answer--no two electrons in an atom can ever have the same
set of quantum numbers
-explains electronic structure of complex atoms as a succession of filled energy levels
with different quantum numbers
and Answers
Compton effect - Answer--the change in wavelength; depends on scattering angle and
not on the wavelength
De Broglie wavelength - Answer--describes wave nature of electrons
-photons have wave and particle characteristics, all forms of matter must have both
-frequency and wavelength can be determined
lambda=h/p= h/mv
f=E/h
Uncertainty Principle - Answer--if a measurement of position of a particle is made with
precision deltax and a simultaneous measurement of linear momentum is made with
precision deltap, then product of 2 uncertainties can never be smaller than h/4pi
-cant know momentum or position at the same time--> always uncertainty
(deltax)(deltap) > h/4pi
suppose we make a measurement of an electrons position. immediately afterwards, we
make a measurement of the e- momentum. immediately after measure e- position again
2nd position measurement will me ______ - Answer-different than the first
How do electrons move to different energy levels - Answer-When energy is added to an
atom, an electron can move from a lower energy level to a higher energy level. The
terms HOMO and LUMO are often used here (Highest Occupied Molecular Orbital and
Lowest Unoccupied Molecular Orbital).
electron energy change and absorption/emission - Answer-An electron in an excited
electronic state can lose energy and change to a state of lower energy. This change of
energy state, or energy level, by an electron in an atom is called an electronic transition.
The energy lost by the atom, the energy difference between the initial and final states, is
emitted as a photon.
transitions between electronic energy levels, observed either as emission or absorption
of light, occur at discrete energies or wavelengths.
emission - Answer--gas at low pressure has a voltage applied to it
-gas emits light which is characteristic of the gas
, -when analyzed with spectrometer, series of discrete bright lines is observed
-spectrum is black background with colorful lights
emission spectrum of hydrogen equation - Answer-1/lambda=Rh(1/2^2 - 2/n^2)
invert and convert to nm
Absorption - Answer--element can absorb light at specific wavelengths
-absorption spectrum can be obtained by passing a continuous radiation spectrum
through a cool vapor of the element being analyzed
-spectrum is colorful with black lines
What can we learn from spectra about an object - Answer-use to identify elements
Calculating PE - Answer-(Ke*e^2)/r
Calculating KE - Answer-1/2mv^2
Calculating total energy - Answer-E = KE + PE
Bohr's Radius - Answer-r= (n^2 (hat)^2)/mke^2
n=1 smallest radius, bohrs radius (a knott)
Principle quantum number - Answer-n
allowed values:1,2,3,4
any number
orbital quantum number - Answer-l
allowed values: n-1
number of allowed states: n
orbital magnetic quantum number - Answer-m(sube)
number of allowed states: 2l +1
allowed values: -l to +l
Pauli exclusion principle - Answer--no two electrons in an atom can ever have the same
set of quantum numbers
-explains electronic structure of complex atoms as a succession of filled energy levels
with different quantum numbers
