Chem I Homework Page, Exam 4 Material

Homework Page with Visible Answers

This page has all of the required homework for the material covered in the fourth exam of the first semester of General Chemistry. The textbook associated with this homework is CHEMISTRY The Central Science by Brown, LeMay, et.al. The last edition I required students to buy was the 12th edition (CHEMISTRY The Central Science, 12th ed. by Brown, LeMay, Bursten, Murphy and Woodward), but any edition of this text will do for this course.

Note: You are expected to go to the end of chapter problems in your textbook, find similar questions, and work out those problems as well. This is just the required list of problems for quiz purposes. You should also study the Exercises within the chapters. The exercises are worked out examples of the questions at the back of the chapter. The study guide also has worked out examples.

These are bare-bones questions. The textbook questions will have additional information that may be useful and that connects the problems to real life applications, many of them in biology.

Electronic Structure (Ch. 6)

  1. Answer the following questions.
  2. List the possible values of the four quantum numbers for:
  3. Identify the following ions using the charges and electron configurations:
  4. Give the electron configurations for each of the following:

    5. Periodic Trends (Ch. 7)

  5. Determine the approximate effective nuclear charge for: (a) Al, (b) Si, (c) P, (d) S, (e) Cl.
    Answer
    The inner electrons and the two 3s electrons would shield all but one of the protons for Al, giving it an effective nuclear charge of +1. Assuming the p electrons don't shield each other, each element would gain an effective nuclear charge of +1 above the last element. So, Si would have +2, P would have +3, S would have +4, and Cl would have +5.

    If you assume the 3s electrons don't shield, the Al atom would have an effective nuclear charge of +3, and so Si would have +4, P would have +5, S would have +6, and Cl would have +7.

  6. Which is the smaller atom, an atom of Al or an atom of Cl? Explain.
    Answer
    Cl would have the smaller atom. As stated in the last problem the effective nuclear charge increases as we go across the table. The larger the effective nuclear charge, the stronger the pull on the electron toward the nucleus and the smaller the atomic size.
  7. Which is bigger: (a) Cl or I, (b) F or F-, (c) Na or Na+? Explain.
    Answer
    (a) Going down the table generally increases the number of protons and electrons so much that the atoms become bigger as we go down the chart. (b) Adding an electron generally makes the ion larger. (c) Taking away an electron generally makes the ion smaller.
  8. Which has the higher first ionization energy: (a) Be or B, (b) As or Se, (c) Ca or Br?
    Answer
    (a) Be, it has a full subshell while B can give one up to have a full subshell. (b) As, it has a half full subshell while Se can give one up to have a half full subshell. (c) Br, it tries to gain an electron while Ca is ready to give up electrons.
  9. Draw the Born-Haber cycle for the formation of KF from potassium metal and fluorine gas.
    Answer
  10. The electron affinity for sodium is -53 kJ/mole and the electron affinity for Mg is greater than zero. Explain.
    Answer
    Mg has a full subshell requiring energy to put another electron into the atom. Na can accept an electron to have a full subshell, even though it prefers to give up an electron to become like a noble gas.
  11. The electron affinity for iodine is -295 kJ/mole and the electron affinity for Xe is greater than zero. Explain.
    Answer
    Xe has a full subshell requiring energy to put another electron into the atom. Iodine can accept an electron to have a full subshell.

    12. Basic Bonding Concepts (Ch. 8)

  12. Using the periodic table predict which element is the most electronegative in the following sets:
    (a) Li, Be, Na, Mg and (b) As, Se, Sb, Te.
    Answer
    (a) Be, (b) Se
  13. Draw the Lewis structures for the following: (a) NO3-, (b) SbF3, (c) H2Se, (d) GeO2, (e)CO2, (f) SiOCl2 (Si is the centeral atom), (g)SH2
    Answer
  14. (a) Draw the resonance structures for the molecule SO3. (b) Draw the picture where all of the resonance structures have been combined. (c) What is the bond order for each of the bonds?
    Answer

    15. Bonding Theories (Ch. 9)

  15. Give the AXE notation, hybrid orbital, electron-domain shape, and molecular shape for the central atom of (a) SeOBr2 (Se is the central atom), (b) BrI4-, (c) BeCl2, (d) PH4+, (e) SeI4, (f) XeCl2, (g) IBr3, (h) AlH3
    Answer
    AXEHybrid OrbitalE-Domain ShapeMolecular Shape
    SeOBr2AX3Esp3TetrahedralTrigonal Pyramidal
    BrI4-AX4E2sp3d2OctahedralSquare Pyramidal
    BeCl2AX2spLinearLinear
    PH4+AX4sp3TetrahedralTetrahedral
    SeI4AX4Esp3dTrigonal BipyramidalSeesaw
    XeCl2AX2E3sp3Trigonal BipyramidalLinear
    IBr3AX3E2sp3dTrigonal BipyramidalT-Shaped
    AlH3AX3Esp3TetrahedralTrigonal Pyramidal
  16. (a) Draw and label the molecular orbital diagrams for F2, F2+, and F2-. (b) Tell whether each is paramagnetic or diamagnetic. (c) Give the bond order of each. (d) Rate them in order of increasing stability.
    Answer