AP EC MC and FR Review
1. All of the following are isoelectronic, EXCEPT which
species?
A. Ne
C. Na+
E. Ar
B. Mg2+
D. F-
2. The first two quantum numbers associated with
various electrons are shown below. Which will have the
lowest energy?
A. 6, 0
C. 4, 2
E. 3, 2
B. 5, 0
D. 5, 1
3. If a photon has frequency = 2.00 x 10 14s-1 and the
speed of light = 3.00 x 108ms-1, then what is its
wavelength?
A. 1500 nm
C. 1.5 nm
E. 1500 m
B. 6.00 x 1022 m
D. 6.02 x 1023
A. Hund's Rule
C. The Bohr model
B. Pauli Exclusion Principle
D. Heisenberg Uncertainty
Principle
E. Planck's constant
10. Which of the following elements has the greatest
number of d electrons?
A. Cr
C. Mn
E. Sn
B. Cu
D. Ge
11. Which pairing is INCORRECT?
A. p orbitals, l=1
B. d orbitals, l=2
C. s orbitals, l=0
D. s orbitals, ml=0
E. d orbitals can have n=1
12. When considering the quantum numbers for a p
orbital, which of the following is true?
4. Which element will the most likely ion of sulfur be
isoelectronic with?
A. He
C. Ar
E. P
9. Which of the following states that any degenrate
orbitals should be filled singlely before any pairing takes
place?
B. Ne
D. Cl
5. Which of the following is NOT possible?
A. 2p6
B. 2d5
6
C. 3p
D. 3s1
7
E. 3d
A. n MUST be 1
C. l MUST be 0
E. None of the Above
B. ms MUST be -1/2
D. ml MUST be +1
13. If the atoms of an element J have the electronic
configuration 1s2 2s2 2p6 3s2 3p4, what is the most likely
formula of a compound it will form with Strontium?
A. SrJ
C. Sr2J
E. Sr2J3
B. SrJ2
D. Sr3J2
6. The electronic configuration of Fe3+ is?
A. [Ar] 4s2 3d5
C. [Ar] 4s1 3d4
E. [Ar] 4s0 3d6
B. [Ar] 4s2 3d3
D. [Ar] 4s0 3d5
7. Which of the following atoms is diamagnetic?
A. H
C. C
E. Al
B. Mg
D. Na
8. Which of the following sets of quantum numbers
could be used to describe the outermost electron in a
Rubidium atom?
A. 5, 1, 1, +1/2
C. 5, 2, 1, -1/2
E. 5, 0, 0, +1/2
B. 5, 0, 1, +1/2
D. 5, 0, 1, -1/2
14. An electron with the quantum numbers 3, 2, +1, +1/2
is in an unfilled sub-level of which atom?
A. Mn
C. Mg
E. P
B. W
D. Na
15. Which electron transition would release the greatest
amount of energy?
A. From n=1 to n=3
C. From n=2 to n=5
E. From n=4 to n=2
B. From n=1 to n=4
D. From n=5 to n=1
16. What is the maximum number of electrons that can
be incorporated into a f sub-shell?
A. 2
C. 14
E. 32
B. 8
D. 18
1980
(a) Write the ground state electron configuration for an arsenic atom, showing the number of electrons in each subshell.
(b) Give one permissible set of four quantum numbers for each of the outermost electrons in a single As atom when it is in its ground state.
(c) Is an isolated arsenic atom in the ground state paramagnetic or diamagnetic? Explain briefly.
(d) Explain how the electron configuration of the arsenic atom in the ground state is consistent with the existence of the following known
compounds: Na3As, AsCl3, and AsF5.
1987
Use the details of modern atomic theory to explain each of the following experimental observations.
(a) Within a family such as the alkali metals, the ionic radius increases as the atomic number increases.
(b) The radius of the chlorine atom is smaller than the radius of the chloride ion, Cl -. (Radii : Cl atom = 0.99Å; Cl− ion = 1.81Å)
(c) The first ionization energy of aluminium is lower than the first ionization energy of magnesium. (First ionization energies: 12Mg
= 7.6 ev; 13Al = 6.0 ev)
(d) For magnesium, the difference between the second and third ionization energies is much larger than the difference between the
first and second ionization energies. (Ionization energies for Mg: 1 st = 7.6 ev; 2nd = 14 ev; 3rd = 80 ev)
1990
The diagram shows the first ionization energies for the elements from Li to Ne. Briefly (in one to three sentences) explain each of the
following in terms of atomic structure.
(a)
(b)
(c)
(d)
In general, there is an increase in the first ionization energy from Li to Ne.
The first ionization energy of B is lower than that of Be.
The first ionization energy of O is lower than that of N.
Predict how the first ionization energy of Na compares to those of Li and of Ne. Explain.
1993
Account for each of the following in terms of principles of atom structure, including the number, properties, and arrangements of
subatomic particles.
(a)
(b)
(c)
(d)
The second ionization energy of sodium is about three times greater than the second ionization
energy of magnesium.
The difference between the atomic radii of Na and K is relatively large compared to the difference between the atomic radii of
Rb and Cs.
A sample of nickel chloride is attracted into a magnetic field, whereas a sample of solid zinc chloride is not.
Phosphorus forms the fluorides PF3 and PF5, whereas nitrogen forms only NF3.
1994 D
Use principles of atomic structure and/or chemical bonding to answer each of the following.
(a) The radius of the Ca atom is 0.197 nanometer; the radius of the Ca 2+ ion is 0.099 nanometer.
Account for this difference.
(b) The lattice energy of CaO(s) is -3,460 kilojoules per mole; the lattice energy for K2O(s) is -2,240 kilojoules per mole. Account
for this difference.
Ionization Energy
(kJ/mol)
First
Second
(c)
K
419
3,050
Ca
590
1,140
Explain the difference between Ca and K in regard to
(i) their first ionization energies,
(ii) their second ionization energies.
The first ionization energy of Mg is 738 kilojoules per mole and that of Al is 578 kilojoules per mole. Account for this
difference.
(d)
1997
Explain each of the following observations using principles of atomic structure and/or bonding.
(a) Potassium has a lower first-ionization energy than lithium.
(b) The ionic radius of N3¯ is larger than that of O2¯.
(c) A calcium atom is larger than a zinc atom.
(d) Boron has a lower first-ionization energy than beryllium.
1999
Answer the following questions regarding light and its interactions with molecules, atoms, and ions.
(a) The longest wavelength of light with enough energy to break the Cl-Cl bond in Cl2(g) is 495 nm.
(i) Calculate the frequency, in s-1, of the light.
(ii) Calculate the energy, in J, of a photon of the light.
(b) A certain line in the spectrum of atomic hydrogen is associated with the electronic transition in the H atom from the
sixth energy level (n = 6) to the second energy level (n = 2).
(i) Indicate whether the H atom emits energy or whether it absorbs energy during the transition. Justify your
answer.
(ii) Calculate the wavelength, in nm, of the radiation associated with the spectral line.
(iii) Account for the observation that the amount of energy associated with the same electronic transition (n =
6 to n = 2) in the He+ ion is greater than that associated with the corresponding transition in the H atom.
2000
Answer the following questions about the element selenium, Se (atomic number 34).
(a) Samples of natural selenium contain six stable isotopes. In terms of atomic structure, explain what these
isotopes have in common, and how they differ.
(b) Write the complete electron configuration (e.g., 1s2 2s2. . . etc.) for a selenium atom in the ground state.
Indicate the number of unpaired electrons in the ground-state atom, and explain your reasoning.
(c) Selenium reacts with fluorine to form SeF4. Draw the complete Lewis electron-dot structure for SeF4 and
sketch the molecular structure. Indicate whether the molecule is polar or nonpolar, and justify your answer
Answers
1. E
2. E
3. A
4. C
5. B
6. D
7. B
8. E
9. A
10. E
11. E
12. E
13. A
14. A
15. D
16. C
1980
a) 2 points
1s2 2s22p6 3s23p6 4s23d104p3
b) 2 points
for the two electrons in the 4s: 4, 0, 0, +1/2 and 4, 0, 0, - 1/2
for the three electrons in the 4p: 4, 1, -1, +1/2; 4, 1, 0, +1/2 and 4, 1, +1, +1/2
c) 2 points
Paramagnetic. It has three unpaired electrons.
d) 2 points
Na3As - each Na gives up one electron to the As, the As has a complete octet and the sodium atoms are
ionically bonded to the arsenic
AsCl3 - the three chlorines each have one half-filled orbital and the aresenic has three. So three covalent
bonds are created and the As has one non-bonding pair to make a pyramidal structure.
AsF5 - fluorine is so eletronegative that it draws the two electrons of the non-bonding pair of AsCl3 into
bonding. A 4d orbital is involved in the sp3d hydridization, yielding a trigonal bipyramidal shape.
2000
(a)
The isotopes have the same number (34) of protons, 1 pt. but a different number of neutrons. 1 pt.
No comment about the number of electrons is necessary
(b) 1 pt.
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4 or
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p4
No point is earned for [Ar] 4s2 3d10 4p4, because the question specifically asks for a complete electron
configuration.
Since there are three different 4p orbitals, there must be two unpaired electrons. 1 pt.