Chemistry 400
Chapter 8 Homework Problems: Periodic Properties of the Elements
1. Imagine an alternate universe in which space unicorns and neon pegasi (the plural form of pegasus) exist. In this world, the value of
the spin quantum number can have only one value (instead of two), ms = 0. Assuming that all other quantum numbers can take only
the possible values in our world and that all of the other rules of quantum mechanics apply (including the Pauli Exclusion Principle).
A. Sketch the shape of the first 5 “periods” of the periodic table including all of the elements in each of these periods.
B. Define paramagnetic and diamagnetic. In this alternate universe, which one doesn’t exist?
2. Imagine a universe in which the value of the spin quantum number can have three values (instead of just two), ms = -1/2, 0, +1/2.
Assuming that all other quantum numbers can take only the possible values in our world and that all of the other rules of quantum
mechanics apply (including the Pauli Exclusion Principle), determine:
A. the electron configuration of Neon
B. the number of the element with a completed n = 2 principal energy level
C. the number of unpaired electrons in fluorine.
3. Write a paragraph about the relationship between the 3d and 4s orbitals in terms of energy. When is 3d lower in energy? When is 4s
lower in energy? To answer this question, use the electron configurations of a potassium atom, a potassium ion, a titanium atom, and a
doubly charged titanium ion.
4. Predict the ground state electron configuration of an atom of:
A. Cesium
B. Selenium
C. Nickel
5. Predict the ground state electron configuration of an atom of:
A. Fluorine
B. Iron
C. Mercury
6. Using a noble gas core, predict the ground state electron configuration of an atom of
A. Sodium
B. Cadmium
C. Lead
7. Using a noble gas core, predict the ground state electron configuration of an atom of
A. Magnesium
B. Tin
C. Gold
8. Using a noble gas core, predict the ground state electron configuration of an ion of
A. Fe3+
B. Cr+2
C. Ag+
9. Using a noble gas core, predict the ground state electron configuration of an ion of
A. V3+
B. I–
C. Cu+
10. Using a noble gas core, predict the ground state electron configuration of an ion of
A. Cr3+
B. Cl–
C. Ag+
11. Write out the first and second ionization reactions for a chlorine atom.
12. Write out the first and second ionization reactions for a copper atom.
13. Write out the first and second electron affinity reactions for an oxygen atom.
14. Write out the first and second electron affinity reactions for an argon atom.
15. Sketch the periodic table and show the trends in atomic size, ionization energy, and electronegativity on it.
16. Identify which of the following sets of quantum numbers {n, l, ml, ms} cannot exist for an electron in an atom and explain why
not:
A. {2,2, –1, +1/2}
B. {6, 0, 0, +1/2}
C. {5, 4, +5, +1/2}
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17. Draw the orbital diagrams (hint: with a box for each orbital and an arrow for each electron) for the following two species that is
consistent with your understanding of the relationship between the 3d/4s, 4d/5s, etc, energy levels:
A. Cl atom
B. Cs+ ion
Energy
Energy
18. Draw the orbital diagrams (hint: with boxes and arrows) for the following two species that is consistent with your understanding of
the relationship between the 3d/4s, 4d/5s, etc, energy levels:
A. Zn atom
B. Cd2+ ion
Energy
Energy
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19. The energy required to move an electron from one level to another in any one-electron system can be approximated as:
$ 1 1'
E = −2.18 ×10−18 J Z2 && 2 − 2 ))
% n2 n1 (
where Z is the atomic number. The first ionization energy for helium is shown in the table below.
€
Ionization
1st
Enthalpy kJ/mol
2372.3
A. Write the first ionization energy reaction for helium. Underneath each atom or ion in the reaction, write out its electron
configuration.
B. Fill in the following "ladder" energy diagram with energy values for each line. The "zero point" energy for this ladder diagram is
DEFINED as the energy of the He2+ ion. All other chemical species will have lower (more negative) energies.
0 kJ/mol ____________ He2+
____________ He+: 4s1
Energy
(kJ/mol)
____________ He+: 3s1
____________ He+: 2s1
____________ He+: 1s1
____________ He: 1s2
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20. The energy required to move an electron from one level to another in any one-electron system can be approximated as:
$ 1 1'
E = −2.18 ×10−18 J Z2 && 2 − 2 ))
% n2 n1 (
where Z is the atomic number. The first and second ionization energies for Lithium are shown in the table below.
€
Ionization
1st
2nd
Enthalpy kJ/mol
520.2
7298.1
A. Write the first and second ionization energy reactions for lithium. Underneath each atom or ion in the reaction, write out its
electron configuration.
B. Fill in the following "ladder" energy diagram with energy values for each line. The "zero point" energy for this ladder diagram is
DEFINED as the energy of the Li3+ ion. All other chemical species will have lower (more negative) energies.
0 kJ/mol ____________ Li3+
____________ Li2+: 3s1
Energy
(kJ/mol)
____________ Li2+: 2s1
____________ Li2+: 1s1
____________ Li+: 1s2
____________ Li: 1s22s1
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