ACS Chemistry 131 FINAL EXAM 2023 |
160 Questions with 100% Correct Answers
1. When looking at the atomic structure what does the left-hand subscript
represent?
• correct answer Atomic number
Rationale: The left-hand subscript in isotopic notation indicates the atomic
number (Z), which equals the number of protons in the nucleus.
2. When looking at the atomic structure what does the left-hand superscript
represent?
• correct answer Mass number
Rationale: The left-hand superscript is the mass number (A), the total
number of protons plus neutrons.
3. Where on the atomic structure would we find the ionic change (if the isotope
has one)?
• correct answer On the right-hand superscript
Rationale: The net ionic charge is written as a superscript on the right side
of the element symbol (e.g., Ca2+ ).
4. The mass number = a combination of what two things?
• correct answer Protons + neutrons
Rationale: Mass number is the total count of nucleons (protons and
neutrons) in the nucleus.
5. The atomic number equals what?
, • correct answer Number of protons
Rationale: The atomic number uniquely identifies an element and is equal to
the proton count.
6. If there is no charge on the isotope what can we assume about its # of
electrons?
• correct answer Electrons = protons
Rationale: A neutral atom has equal numbers of protons (positive) and
electrons (negative).
7. What is the definition of an isotope?
• correct answer Forms of the same element that differ only in number of
neutrons
Rationale: Isotopes have identical atomic numbers but different mass
numbers due to varying neutron counts.
8. Give an example of an isotope.
• correct answer 12 6 𝐶 and
14
6 𝐶
*Rationale: Carbon-12 and carbon-14 have the same number of protons (6)
but different neutrons (6 vs 8).*
9. What particle can you remove from a nucleus and have no change to an
element’s atomic number?
• correct answer Neutron
Rationale: Removing a neutron changes the mass number but not the
proton count, so the element remains the same (just a different isotope).
10. What type of charge is associated with the following: proton, alpha particle,
beta particle, neutron?
, • correct answer Proton: +1, Alpha: +2, Beta: –1, Neutron: 0
*Rationale: Proton = +1 elementary charge; alpha particle = helium nucleus
(2 protons) = +2; beta particle = electron = –1; neutron = neutral.*
11. What was concluded from Ernest Rutherford’s experiment?
• correct answer Most of the atom is empty space; mass and positive charge
are concentrated in a tiny nucleus
Rationale: The gold foil experiment showed most alpha particles passed
through, but some were deflected, indicating a small, dense, positively
charged nucleus.
12. List the Electromagnetic Spectrum for photons/light going from greatest to
least (energy/frequency).
• correct answer X-rays, Ultraviolet, Visible Light, Infrared, Microwaves, TV,
Radio Waves
Rationale: Order from high frequency/short wavelength to low
frequency/long wavelength.
13. X-Ray will have the highest _____ and the shortest _____.
• correct answer frequency; wavelength
Rationale: Energy is directly proportional to frequency and inversely
proportional to wavelength.
14. Radio Waves will have the lowest _____ and longest _____.
• correct answer frequencies; wavelength
Rationale: Radio waves are at the low-energy end of the EM spectrum.
15. Emission vs. Absorption for electron transitions.
160 Questions with 100% Correct Answers
1. When looking at the atomic structure what does the left-hand subscript
represent?
• correct answer Atomic number
Rationale: The left-hand subscript in isotopic notation indicates the atomic
number (Z), which equals the number of protons in the nucleus.
2. When looking at the atomic structure what does the left-hand superscript
represent?
• correct answer Mass number
Rationale: The left-hand superscript is the mass number (A), the total
number of protons plus neutrons.
3. Where on the atomic structure would we find the ionic change (if the isotope
has one)?
• correct answer On the right-hand superscript
Rationale: The net ionic charge is written as a superscript on the right side
of the element symbol (e.g., Ca2+ ).
4. The mass number = a combination of what two things?
• correct answer Protons + neutrons
Rationale: Mass number is the total count of nucleons (protons and
neutrons) in the nucleus.
5. The atomic number equals what?
, • correct answer Number of protons
Rationale: The atomic number uniquely identifies an element and is equal to
the proton count.
6. If there is no charge on the isotope what can we assume about its # of
electrons?
• correct answer Electrons = protons
Rationale: A neutral atom has equal numbers of protons (positive) and
electrons (negative).
7. What is the definition of an isotope?
• correct answer Forms of the same element that differ only in number of
neutrons
Rationale: Isotopes have identical atomic numbers but different mass
numbers due to varying neutron counts.
8. Give an example of an isotope.
• correct answer 12 6 𝐶 and
14
6 𝐶
*Rationale: Carbon-12 and carbon-14 have the same number of protons (6)
but different neutrons (6 vs 8).*
9. What particle can you remove from a nucleus and have no change to an
element’s atomic number?
• correct answer Neutron
Rationale: Removing a neutron changes the mass number but not the
proton count, so the element remains the same (just a different isotope).
10. What type of charge is associated with the following: proton, alpha particle,
beta particle, neutron?
, • correct answer Proton: +1, Alpha: +2, Beta: –1, Neutron: 0
*Rationale: Proton = +1 elementary charge; alpha particle = helium nucleus
(2 protons) = +2; beta particle = electron = –1; neutron = neutral.*
11. What was concluded from Ernest Rutherford’s experiment?
• correct answer Most of the atom is empty space; mass and positive charge
are concentrated in a tiny nucleus
Rationale: The gold foil experiment showed most alpha particles passed
through, but some were deflected, indicating a small, dense, positively
charged nucleus.
12. List the Electromagnetic Spectrum for photons/light going from greatest to
least (energy/frequency).
• correct answer X-rays, Ultraviolet, Visible Light, Infrared, Microwaves, TV,
Radio Waves
Rationale: Order from high frequency/short wavelength to low
frequency/long wavelength.
13. X-Ray will have the highest _____ and the shortest _____.
• correct answer frequency; wavelength
Rationale: Energy is directly proportional to frequency and inversely
proportional to wavelength.
14. Radio Waves will have the lowest _____ and longest _____.
• correct answer frequencies; wavelength
Rationale: Radio waves are at the low-energy end of the EM spectrum.
15. Emission vs. Absorption for electron transitions.
