CEM 141 EXAM 1 2026 STOICHIOMETRY AND
CALCULATIONS WORKBOOK SOLVED
QUESTIONS COMPILATION
◉ why we consider light a wave (claim, evidence, reasoning).
Answer: 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.
Answer: 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.
Answer: Einstein postulated light must come in packets (particles or
quanta)
◉ energy.
Answer: E=hv
, h=6.626x10^-34 J/s
◉ visible spectrum.
Answer: light from the sun (white light) can be separated by a prism
(first done by Newton)
◉ atomic emission spectrum.
Answer: 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.
Answer: The characteristic line spectrum that occurs as a result of
energy being absorbed by individual elements. Black lines on a
continuum (coloured) background.
◉ spectra.
Answer: shows light at specific wavelength and energies
◉ Bohr model of atom.
Answer: explained emission/absorption spectra by invoking
discrete energy levels characterized by quantum numbers (n).
CALCULATIONS WORKBOOK SOLVED
QUESTIONS COMPILATION
◉ why we consider light a wave (claim, evidence, reasoning).
Answer: 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.
Answer: 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.
Answer: Einstein postulated light must come in packets (particles or
quanta)
◉ energy.
Answer: E=hv
, h=6.626x10^-34 J/s
◉ visible spectrum.
Answer: light from the sun (white light) can be separated by a prism
(first done by Newton)
◉ atomic emission spectrum.
Answer: 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.
Answer: The characteristic line spectrum that occurs as a result of
energy being absorbed by individual elements. Black lines on a
continuum (coloured) background.
◉ spectra.
Answer: shows light at specific wavelength and energies
◉ Bohr model of atom.
Answer: explained emission/absorption spectra by invoking
discrete energy levels characterized by quantum numbers (n).
