Principles of Chemistry Final Exam
Review with Answers
accuracy - correct answer-How close to the true value a given measurement is.
precise - correct answer-How well a number of independent measurements agree with
each other.
atomic number - correct answer-(Z)
• Number of protons in an atom's nucleus
• Equivalent to the number of electrons around the atom's nucleus
mass number - correct answer-(A)
The sum of the number of protons (Z) and neutrons (N) in an atom's nucleus.
A=Z+N
isotope - correct answer-Atoms with identical atomic numbers but different mass
numbers.
(Different atoms of the same element can have different mass numbers depending on
how many neutrons each
has.)
atomic weight - correct answer-The weighted average of the atomic masses of the
element's naturally occurring isotopes.
molar mass - correct answer-• Mass in grams of one mole of any element.
• Numerically it is equivalent to its molecular or
formula weight.
• Use molar mass to convert between moles and grams.
planck's postulate - correct answer-How to calculate the energy of a photon
E = hν
E = hc/λ
• h (Planck's constant) = 6.626 × 10-34 J s
• c = 3.00 x 108 m/s (speed of light)
• λ (lambda) must be in meters!
• 1 nm = 10-9 m
principal quantum number - correct answer-(n)
Distance from the nucleus! Describes the size and energy level of the orbital!
• Positive integer (n = 1, 2, 3, 4, ...)
, • Commonly called shell
• As the value of n increases:
• The energy of the electron in the orbital increases
• The distance of the electron from the nucleus increases
angular momentum quantum number - correct answer-(l)
Shape of the orbital!
• Possible values (n = 0, 1, 2, 3, 4,..., (n-1)
magnetic quantum number - correct answer-(m₁)
Orientation in space!
• Possible values (-l,...,-1, 0, 1,..., l)
spin quantum number - correct answer-(m (subscript)s)
Electron spin!
• Possible values (-1/2, +1/2)
electron configuration - correct answer-A description of which orbitals are occupied by
electrons.
ground-state electron configuration - correct answer-The lowest energy configuration.
aufbau principle - correct answer-A set of guidelines for the filling order of orbitals.
• Add electrons one-by-one to the lowest-energy
orbital available.
• An orbital can only hold two electrons, which must
have opposite spins (Pauli exclusion principle).
• If two or more orbitals of equal energy are available,
one electron goes into each until all are half-full. The
electrons in the half-filled orbitals are parallel.
(Hund's rule)
valence shell - correct answer-Outermost shell.
• These electrons, as they are outermost and
least tightly held, determine an element's properties. That is why elements in a given
group have similar chemical properties.
atomic radii - correct answer-Generally:
• Increase going down a group because larger valence-shell orbitals are occupied.
• Decrease going from left to right because the number of protons increases, which
increases Zeff.
effective nuclear charge - correct answer-Zeff = Zactual - Electron Shielding
• Z represents nuclear charge
• Zeff: nuclear charge actually felt by the electron
• Zactual: full nuclear charge, pulls the electrons in
Review with Answers
accuracy - correct answer-How close to the true value a given measurement is.
precise - correct answer-How well a number of independent measurements agree with
each other.
atomic number - correct answer-(Z)
• Number of protons in an atom's nucleus
• Equivalent to the number of electrons around the atom's nucleus
mass number - correct answer-(A)
The sum of the number of protons (Z) and neutrons (N) in an atom's nucleus.
A=Z+N
isotope - correct answer-Atoms with identical atomic numbers but different mass
numbers.
(Different atoms of the same element can have different mass numbers depending on
how many neutrons each
has.)
atomic weight - correct answer-The weighted average of the atomic masses of the
element's naturally occurring isotopes.
molar mass - correct answer-• Mass in grams of one mole of any element.
• Numerically it is equivalent to its molecular or
formula weight.
• Use molar mass to convert between moles and grams.
planck's postulate - correct answer-How to calculate the energy of a photon
E = hν
E = hc/λ
• h (Planck's constant) = 6.626 × 10-34 J s
• c = 3.00 x 108 m/s (speed of light)
• λ (lambda) must be in meters!
• 1 nm = 10-9 m
principal quantum number - correct answer-(n)
Distance from the nucleus! Describes the size and energy level of the orbital!
• Positive integer (n = 1, 2, 3, 4, ...)
, • Commonly called shell
• As the value of n increases:
• The energy of the electron in the orbital increases
• The distance of the electron from the nucleus increases
angular momentum quantum number - correct answer-(l)
Shape of the orbital!
• Possible values (n = 0, 1, 2, 3, 4,..., (n-1)
magnetic quantum number - correct answer-(m₁)
Orientation in space!
• Possible values (-l,...,-1, 0, 1,..., l)
spin quantum number - correct answer-(m (subscript)s)
Electron spin!
• Possible values (-1/2, +1/2)
electron configuration - correct answer-A description of which orbitals are occupied by
electrons.
ground-state electron configuration - correct answer-The lowest energy configuration.
aufbau principle - correct answer-A set of guidelines for the filling order of orbitals.
• Add electrons one-by-one to the lowest-energy
orbital available.
• An orbital can only hold two electrons, which must
have opposite spins (Pauli exclusion principle).
• If two or more orbitals of equal energy are available,
one electron goes into each until all are half-full. The
electrons in the half-filled orbitals are parallel.
(Hund's rule)
valence shell - correct answer-Outermost shell.
• These electrons, as they are outermost and
least tightly held, determine an element's properties. That is why elements in a given
group have similar chemical properties.
atomic radii - correct answer-Generally:
• Increase going down a group because larger valence-shell orbitals are occupied.
• Decrease going from left to right because the number of protons increases, which
increases Zeff.
effective nuclear charge - correct answer-Zeff = Zactual - Electron Shielding
• Z represents nuclear charge
• Zeff: nuclear charge actually felt by the electron
• Zactual: full nuclear charge, pulls the electrons in
