CEM 141 FINAL EXAM 2026 CHEMICAL
REACTIONS AND STOICHIOMETRY REVIEW
QUESTIONS ANSWERS VERIFIED GUIDE
◉ Lights acts as what?
Answer: Particle and wave.
◉ scientific model
Answer: drawing, graph, diagram, equation. represent many
chemical entities.
◉ Wavelength
Answer: The distance (m) of waves from peak to peak. Short: x-ray
(red), long: infrared (blue)
Short - higher energy
Long - lower energy
◉ scientific theory
Answer: 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)
Answer: The number of wavefronts per second. Highest: x-ray
◉ scientific law
Answer: 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
Answer: C = 3.00 X 10^8
= wavelength X frequency
◉ scientific explanation
Answer: claim, evidence, reasoning
◉ Amplitude
Answer: The intensity, height of peaks of waves. Highest: blue light
◉ size of an atom
Answer: 0.1 x 10^-9m
◉ Energy of Wave (J)
,Answer: Increases as frequency increases and as wavelength
decreases. Highest: x-ray
◉ Greek philosophers atomic theory
Answer: -first atomic theory
-elements: earth, fire, water, air
-constantly in motion
-made of mostly empty space
◉ Range of Wavelengths
Answer: 10^-16 - 10^8 = 24. Only a third are visible
◉ Black Body Radiation
Answer: 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 ___
Answer: the observable properties
◉ atom
Answer: smallest distinguishable part of an element
, ◉ Photoelectric Effect
Answer: 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?
Answer: 91 naturally occurring elements
◉ How many electrons are emitted if the light is below it's threshold
frequency no matter the intensity?
Answer: None.
◉ Dalton's atomic theory (1800s)
Answer: -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
REACTIONS AND STOICHIOMETRY REVIEW
QUESTIONS ANSWERS VERIFIED GUIDE
◉ Lights acts as what?
Answer: Particle and wave.
◉ scientific model
Answer: drawing, graph, diagram, equation. represent many
chemical entities.
◉ Wavelength
Answer: The distance (m) of waves from peak to peak. Short: x-ray
(red), long: infrared (blue)
Short - higher energy
Long - lower energy
◉ scientific theory
Answer: 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)
Answer: The number of wavefronts per second. Highest: x-ray
◉ scientific law
Answer: 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
Answer: C = 3.00 X 10^8
= wavelength X frequency
◉ scientific explanation
Answer: claim, evidence, reasoning
◉ Amplitude
Answer: The intensity, height of peaks of waves. Highest: blue light
◉ size of an atom
Answer: 0.1 x 10^-9m
◉ Energy of Wave (J)
,Answer: Increases as frequency increases and as wavelength
decreases. Highest: x-ray
◉ Greek philosophers atomic theory
Answer: -first atomic theory
-elements: earth, fire, water, air
-constantly in motion
-made of mostly empty space
◉ Range of Wavelengths
Answer: 10^-16 - 10^8 = 24. Only a third are visible
◉ Black Body Radiation
Answer: 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 ___
Answer: the observable properties
◉ atom
Answer: smallest distinguishable part of an element
, ◉ Photoelectric Effect
Answer: 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?
Answer: 91 naturally occurring elements
◉ How many electrons are emitted if the light is below it's threshold
frequency no matter the intensity?
Answer: None.
◉ Dalton's atomic theory (1800s)
Answer: -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
