CEM 141 - Exam 2 Exam Questions
and Answers
mole - -6.022 x 10^23 things
number of particles that allows us to convert from the molecular to the
macroscopic level
- limiting reactant/reagent - -amount of one of the reactants which limits
how much product can be formed. smallest amount.
- percent yield - -actual/theoretical x 100
- electromagnetic radiation - -
- wavelength - -The distance between two corresponding parts of a wave.
seconds/wave. 1/frequency. measured in m
- amplitude - -Height of a wave
- frequency - -waves/second. 1/wavelength. measured in Hz
- Constant (c) - -3 x 10^8 m/s. c=(wavelength)(frequency)
- constructive interference - -The interference that occurs when two waves
combine to make a wave with a larger amplitude = brighter
- destructive interference - -The interference that occurs when two waves
combine to make a wave with a smaller amplitude = darker
- diffraction - -The bending of a wave as it moves around an obstacle or
passes through a narrow opening
- models of light - -light as a wave/particle
- photoelectric effect - -The emission of electrons from a metal when light
shines on the metal.
- why is light considered a wave (evidence) - -diffraction, interference
- why we consider light a wave (claim, evidence, reasoning) - -claim-light is
a wave
evidence- diffraction, interference
reasoning- light acts the same as waves as demonstrated in diffraction and
interference.
, - why is light considered a particle - -photoelectric effect. there is a
threshold frequency below which no electrons are emitted from metal when
light is shined . if light were a wave, the intensity should increase the energy
and eject electrons.
- photon - -Einstein postulated light must come in packets (particles or
quanta)
- energy - -E=hv
h=6.626x10^-34 J/s
- visible spectrum - -light from the sun (white light) can be separated by a
prism (first done by Newton)
- atomic emission spectrum - -light from one particular element does not
contain all the colors of the spectrum, only few wavelengths.
The discontinuous line spectra of light produced when excited atoms return
to their ground state and emit photons of a certain frequency.
- atomic absorption spectrum - -The characteristic line spectrum that occurs
as a result of energy being absorbed by individual elements. Black lines on a
continuum (coloured) background.
- spectra - -shows light at specific wavelength and energies
- Bohr model of atom - -explained emission/absorption spectra by invoking
discrete energy levels characterized by quantum numbers (n). photons of
e/m energy are emitted from atoms as electrons move from one energy level
to another. ONLY WORKS FOR HYDROGEN
- atomic excitation - -excites orbital electron to higher energy level
- atomic de-excitation - -de-excites orbital electron to lower energy level.
- energy diagrams - atom - --each energy level has a different number.
-higher numbers=higher energy level.
-energy levels are not orbitals.
-electrons transition between energy levels by absorbing or emitting photons
- emission - -release of energy
- absorption - -gaining energy
and Answers
mole - -6.022 x 10^23 things
number of particles that allows us to convert from the molecular to the
macroscopic level
- limiting reactant/reagent - -amount of one of the reactants which limits
how much product can be formed. smallest amount.
- percent yield - -actual/theoretical x 100
- electromagnetic radiation - -
- wavelength - -The distance between two corresponding parts of a wave.
seconds/wave. 1/frequency. measured in m
- amplitude - -Height of a wave
- frequency - -waves/second. 1/wavelength. measured in Hz
- Constant (c) - -3 x 10^8 m/s. c=(wavelength)(frequency)
- constructive interference - -The interference that occurs when two waves
combine to make a wave with a larger amplitude = brighter
- destructive interference - -The interference that occurs when two waves
combine to make a wave with a smaller amplitude = darker
- diffraction - -The bending of a wave as it moves around an obstacle or
passes through a narrow opening
- models of light - -light as a wave/particle
- photoelectric effect - -The emission of electrons from a metal when light
shines on the metal.
- why is light considered a wave (evidence) - -diffraction, interference
- why we consider light a wave (claim, evidence, reasoning) - -claim-light is
a wave
evidence- diffraction, interference
reasoning- light acts the same as waves as demonstrated in diffraction and
interference.
, - why is light considered a particle - -photoelectric effect. there is a
threshold frequency below which no electrons are emitted from metal when
light is shined . if light were a wave, the intensity should increase the energy
and eject electrons.
- photon - -Einstein postulated light must come in packets (particles or
quanta)
- energy - -E=hv
h=6.626x10^-34 J/s
- visible spectrum - -light from the sun (white light) can be separated by a
prism (first done by Newton)
- atomic emission spectrum - -light from one particular element does not
contain all the colors of the spectrum, only few wavelengths.
The discontinuous line spectra of light produced when excited atoms return
to their ground state and emit photons of a certain frequency.
- atomic absorption spectrum - -The characteristic line spectrum that occurs
as a result of energy being absorbed by individual elements. Black lines on a
continuum (coloured) background.
- spectra - -shows light at specific wavelength and energies
- Bohr model of atom - -explained emission/absorption spectra by invoking
discrete energy levels characterized by quantum numbers (n). photons of
e/m energy are emitted from atoms as electrons move from one energy level
to another. ONLY WORKS FOR HYDROGEN
- atomic excitation - -excites orbital electron to higher energy level
- atomic de-excitation - -de-excites orbital electron to lower energy level.
- energy diagrams - atom - --each energy level has a different number.
-higher numbers=higher energy level.
-energy levels are not orbitals.
-electrons transition between energy levels by absorbing or emitting photons
- emission - -release of energy
- absorption - -gaining energy
