MSU CEM 141 FINAL EXAM
QUESTIONS AND ANSWERS 2026
scientific question - ANSWERScan be answered by doing experiments, making
observation, taking measurements, etc. in a replicable way
Lights acts as what? - ANSWERSParticle and wave.
scientific model - ANSWERSdrawing, graph, diagram, equation. represent many
chemical entities.
Wavelength - ANSWERSThe distance (m) of waves from peak to peak. Short: x-ray
(red), long: infrared (blue)
Short - higher energy
Long - lower energy
scientific theory - ANSWERSA well tested concept that explains a wide range of
observations (explains why). changes with time. Explains the underlying cause of a
range of phenomena
Frequency (V) - ANSWERSThe number of wavefronts per second. Highest: x-ray
scientific law - ANSWERSA theory that has been tested by and is consistent with
generations of data. a rule that describes a pattern in nature (explains what)
Velocity of Light - ANSWERSC = 3.00 X 10^8
= wavelength X frequency
scientific explanation - ANSWERSclaim, evidence, reasoning
Amplitude - ANSWERSThe intensity, height of peaks of waves. Highest: blue light
size of an atom - ANSWERS0.1 x 10^-9m
Energy of Wave (J) - ANSWERSIncreases as frequency increases and as wavelength
decreases. Highest: x-ray
Greek philosophers atomic theory - ANSWERS-first atomic theory
-elements: earth, fire, water, air
-constantly in motion
,-made of mostly empty space
Range of Wavelengths - ANSWERS10^-16 - 10^8 = 24. Only a third are visible
Black Body Radiation - ANSWERSWhen a mass is heated it emits a type of EM
radiation, at very high temps the mass becomes "white hot" because all wavelengths of
visible light become equally intense
molecular structure of a substance determines ___ - ANSWERSthe observable
properties
atom - ANSWERSsmallest distinguishable part of an element
Photoelectric Effect - ANSWERSMetals emit electrons when electromagnetic radiation
shines on the surface, light is transfers energy to the electrons at the metal's surface
where it's transformed into KE that gives the electrons enough energy to leave the atom
Depends on frequency not intensity
how many atoms are naturally occurring? - ANSWERS91 naturally occurring elements
How many electrons are emitted if the light is below it's threshold frequency no matter
the intensity? - ANSWERSNone.
Dalton's atomic theory (1800s) - ANSWERS-elements composed of small, indivisible,
indestructible, particles (atoms)
-all atoms of each element are identical (mass/properties)
-no subatomic particles
-compounds are formed by combos of atoms from 2+ elements
-chemical reactions occur from rearrangement of atoms
What increases the number of electrons to be emitted by the photoelectric effect? -
ANSWERSIntensity.
JJ Thomson - ANSWERS-first person to provide evidence of electron
-cathode ray tube
-plum pudding model
-particles carried electric charge
A particle that transfers light energy with a definable energy, emits one electron
energy of = h (6.626 x 10^-34 J) - ANSWERSPhoton.
cathode ray tube - ANSWERS-JJ Thomson
-electron particles were emitted from cathodes
-particles carried electric charge
-ray was independent of the element it came from
-particles identical regardless of cathode
, -proved all atoms contained electrons
Energy of light equation? - ANSWERSE = hV.
plum pudding model - ANSWERS-atoms contained electrons embedded in the middle
-JJ Thomson
h - ANSWERSPlanck's constant, the energy of a photon.
alpha particle - ANSWERS2 neutrons, 2 protons
What happens to the energy when there is a short wavelength? - ANSWERSHigh
energy.
Light from the sun (white light) can be separated by a prism to create this, only a small
part of the full EM spectrum? - ANSWERSVisible Spectrum.
Rutherford - ANSWERS-gold foil experiment
-atoms mostly empty space
-small, dense, positively charged nucleus
Gold foil experiment - ANSWERS-most particles went straight through
-every once in awhile particles were deflected
-1/8000 particles bounced back
-led to model of atom; small, dense, positively charged nucleus
Atomic Emission Spectrum - ANSWERSSpectrum that emits photons, energy diagram:
electron goes down energy levels.
neutrons - ANSWERS-discovered in 1932
-slightly heavier than protons
Atomic Absorption Spectrum - ANSWERSSpectrum that absorbs photons, energy
diagram: electrons goes up in energy levels.
Current model of atom - ANSWERS-nucleus contains protons and neutrons
-cloud of electrons
Heisenberg Uncertainty Principle - ANSWERSPrinciple states that we can't accurately
measure both the position and the energy of a small particle (electron)
Bohr's model did - why its wrong.
charges of electrons, protons, neutrons - ANSWERS-electrons: -1, 1/3000 amu
-protons: +1, 1 amu
-neutrons: 0 charge, 1 amu
QUESTIONS AND ANSWERS 2026
scientific question - ANSWERScan be answered by doing experiments, making
observation, taking measurements, etc. in a replicable way
Lights acts as what? - ANSWERSParticle and wave.
scientific model - ANSWERSdrawing, graph, diagram, equation. represent many
chemical entities.
Wavelength - ANSWERSThe distance (m) of waves from peak to peak. Short: x-ray
(red), long: infrared (blue)
Short - higher energy
Long - lower energy
scientific theory - ANSWERSA well tested concept that explains a wide range of
observations (explains why). changes with time. Explains the underlying cause of a
range of phenomena
Frequency (V) - ANSWERSThe number of wavefronts per second. Highest: x-ray
scientific law - ANSWERSA theory that has been tested by and is consistent with
generations of data. a rule that describes a pattern in nature (explains what)
Velocity of Light - ANSWERSC = 3.00 X 10^8
= wavelength X frequency
scientific explanation - ANSWERSclaim, evidence, reasoning
Amplitude - ANSWERSThe intensity, height of peaks of waves. Highest: blue light
size of an atom - ANSWERS0.1 x 10^-9m
Energy of Wave (J) - ANSWERSIncreases as frequency increases and as wavelength
decreases. Highest: x-ray
Greek philosophers atomic theory - ANSWERS-first atomic theory
-elements: earth, fire, water, air
-constantly in motion
,-made of mostly empty space
Range of Wavelengths - ANSWERS10^-16 - 10^8 = 24. Only a third are visible
Black Body Radiation - ANSWERSWhen a mass is heated it emits a type of EM
radiation, at very high temps the mass becomes "white hot" because all wavelengths of
visible light become equally intense
molecular structure of a substance determines ___ - ANSWERSthe observable
properties
atom - ANSWERSsmallest distinguishable part of an element
Photoelectric Effect - ANSWERSMetals emit electrons when electromagnetic radiation
shines on the surface, light is transfers energy to the electrons at the metal's surface
where it's transformed into KE that gives the electrons enough energy to leave the atom
Depends on frequency not intensity
how many atoms are naturally occurring? - ANSWERS91 naturally occurring elements
How many electrons are emitted if the light is below it's threshold frequency no matter
the intensity? - ANSWERSNone.
Dalton's atomic theory (1800s) - ANSWERS-elements composed of small, indivisible,
indestructible, particles (atoms)
-all atoms of each element are identical (mass/properties)
-no subatomic particles
-compounds are formed by combos of atoms from 2+ elements
-chemical reactions occur from rearrangement of atoms
What increases the number of electrons to be emitted by the photoelectric effect? -
ANSWERSIntensity.
JJ Thomson - ANSWERS-first person to provide evidence of electron
-cathode ray tube
-plum pudding model
-particles carried electric charge
A particle that transfers light energy with a definable energy, emits one electron
energy of = h (6.626 x 10^-34 J) - ANSWERSPhoton.
cathode ray tube - ANSWERS-JJ Thomson
-electron particles were emitted from cathodes
-particles carried electric charge
-ray was independent of the element it came from
-particles identical regardless of cathode
, -proved all atoms contained electrons
Energy of light equation? - ANSWERSE = hV.
plum pudding model - ANSWERS-atoms contained electrons embedded in the middle
-JJ Thomson
h - ANSWERSPlanck's constant, the energy of a photon.
alpha particle - ANSWERS2 neutrons, 2 protons
What happens to the energy when there is a short wavelength? - ANSWERSHigh
energy.
Light from the sun (white light) can be separated by a prism to create this, only a small
part of the full EM spectrum? - ANSWERSVisible Spectrum.
Rutherford - ANSWERS-gold foil experiment
-atoms mostly empty space
-small, dense, positively charged nucleus
Gold foil experiment - ANSWERS-most particles went straight through
-every once in awhile particles were deflected
-1/8000 particles bounced back
-led to model of atom; small, dense, positively charged nucleus
Atomic Emission Spectrum - ANSWERSSpectrum that emits photons, energy diagram:
electron goes down energy levels.
neutrons - ANSWERS-discovered in 1932
-slightly heavier than protons
Atomic Absorption Spectrum - ANSWERSSpectrum that absorbs photons, energy
diagram: electrons goes up in energy levels.
Current model of atom - ANSWERS-nucleus contains protons and neutrons
-cloud of electrons
Heisenberg Uncertainty Principle - ANSWERSPrinciple states that we can't accurately
measure both the position and the energy of a small particle (electron)
Bohr's model did - why its wrong.
charges of electrons, protons, neutrons - ANSWERS-electrons: -1, 1/3000 amu
-protons: +1, 1 amu
-neutrons: 0 charge, 1 amu
