MSU CEM 141 FINAL EXAM WITH
COMPLETE SOLUTIONS
scientific question ✔✔can be answered by doing experiments, making observation, taking measurements, etc. in a replicable way
Lights acts as what? ✔✔Particle and wave.
scientific model ✔✔drawing, graph, diagram, equation. represent many chemical entities.
Wavelength ✔✔The distance (m) of waves from peak to peak. Short: x-ray (red), long: infrared (blue) Short - higher energy Long - lower energy
scientific theory ✔✔A 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) ✔✔The number of wavefronts per second. Highest: x-ray 1 / 4
scientific law ✔✔A 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 ✔✔C = 3.00 X 10^8 = wavelength X frequency
scientific explanation ✔✔claim, evidence, reasoning
Amplitude ✔✔The intensity, height of peaks of waves. Highest: blue light
size of an atom ✔✔0.1 x 10^-9m
Energy of Wave (J) ✔✔Increases as frequency increases and as wavelength decreases. Highest: x-ray
Greek philosophers atomic theory ✔✔-first atomic theory
-elements: earth, fire, water, air 2 / 4
-constantly in motion -made of mostly empty space
Range of Wavelengths ✔✔10^-16 - 10^8 = 24. Only a third are visible
Black Body Radiation ✔✔When 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 ___ ✔✔the observable properties
atom ✔✔smallest distinguishable part of an element
Photoelectric Effect ✔✔Metals 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? ✔✔91 naturally occurring elements 3 / 4
How many electrons are emitted if the light is below it's threshold frequency no matter the intensity? ✔✔None.
Dalton's atomic theory (1800s) ✔✔-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? ✔✔Intensity.
JJ Thomson ✔✔-first person to provide evidence of electron -cathode ray tube -plum pudding model -particles carried electric charge
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