Friday, December 15, 2006
AP Bonding II Exam
Okay, on the class website, there is a RIDICULOUS number of practice questions/files with answers as well as tutorials for Monday's bonding test.
For our test on Monday:
Most of our time and therefore most of our test will be on all of the types of molecules or ions that we drew out in our grand chart. So anything and everything on that chart will be asked for.
Be able to show the orbital hybridization that occurs on a CENTRAL atom starting with the orbital diagram of the un-hybridized atom. Then show the electron shifts that occur in order to form the proper bonding arrangement in the molecule. For example, in CH4, carbon has a valence electron configuration of 2s2 2p2, which had only two unpaired electrons available for bonding. Not only that, the unpaired p electrons are in perpendicular p orbitals. So, in order to explain the four bonds that form in a tetrahedral arrangement, the C must hybridize its 2s and all three 2p orbitals to form FOUR equal energy, tetrahedrally oriented sp3 orbitals. As bonds form, these sp3 orbitals overlap with the Hydrogen 1s orbital (that is all that H has occupied with one electron; generally don't worry about hybridization of terminal atoms unless there is only one type of hybridization that can apply) and the opposite spin electron pairs (one from each atom in this case) form a bond between each pair of atomic nuclei.
For intermolecular attractions, know the different types: induced dipole, dipole-dipole, and extreme dipole-dipole (hydrogen bonding) attractions. Based on electronic and molecular geometry from your Lewis structure and VSEPR, predict the molecular polarity and the expected dominant intermolecular type of attraction. For example, CF4 has tetrahedral electronic and molecular geometry, which results in a symmetric distribution of charge/electrons. The molecule is therefore nonpolar because there is, on average, no net partial positive or partial negative "side" of the molecule so its intermolecular forces of attraction are induced dipole attractions.
Know how to reproduce the molecular orbital diagrams from the starting atomic orbitals. Check out the text and powerpoint to check your diagram. Remember the first FIVE diatomics in period two (from left to right) are the "feminine-shaped" diagrams (ladies first) and the last three O2, F2, and Ne2 are the "masculine-shaped" diagrams. Know how to predict bond order, bond length, bond strength/BDE, para or diamagnetism from the diagrams of these diatomic molecules OR ions. Here is a great site for pictures and review of MO Theory:
http://www.chem.latech.edu/~upali/chem281/281GRCc3.htm
Here's another good site that walks you through most of the bonding subtopics with nice graphics:
http://highered.mcgraw-hill.com/sites/0073656011/student_view0/chapter10/essential_study_partner.html
The text sections 10.5 and 10.6 gets into MO Theory (the answer to those sections' questions are posted now) and there is the Bonding II study guide that has MO theory and questions.
For our test on Monday:
Most of our time and therefore most of our test will be on all of the types of molecules or ions that we drew out in our grand chart. So anything and everything on that chart will be asked for.
Be able to show the orbital hybridization that occurs on a CENTRAL atom starting with the orbital diagram of the un-hybridized atom. Then show the electron shifts that occur in order to form the proper bonding arrangement in the molecule. For example, in CH4, carbon has a valence electron configuration of 2s2 2p2, which had only two unpaired electrons available for bonding. Not only that, the unpaired p electrons are in perpendicular p orbitals. So, in order to explain the four bonds that form in a tetrahedral arrangement, the C must hybridize its 2s and all three 2p orbitals to form FOUR equal energy, tetrahedrally oriented sp3 orbitals. As bonds form, these sp3 orbitals overlap with the Hydrogen 1s orbital (that is all that H has occupied with one electron; generally don't worry about hybridization of terminal atoms unless there is only one type of hybridization that can apply) and the opposite spin electron pairs (one from each atom in this case) form a bond between each pair of atomic nuclei.
For intermolecular attractions, know the different types: induced dipole, dipole-dipole, and extreme dipole-dipole (hydrogen bonding) attractions. Based on electronic and molecular geometry from your Lewis structure and VSEPR, predict the molecular polarity and the expected dominant intermolecular type of attraction. For example, CF4 has tetrahedral electronic and molecular geometry, which results in a symmetric distribution of charge/electrons. The molecule is therefore nonpolar because there is, on average, no net partial positive or partial negative "side" of the molecule so its intermolecular forces of attraction are induced dipole attractions.
Know how to reproduce the molecular orbital diagrams from the starting atomic orbitals. Check out the text and powerpoint to check your diagram. Remember the first FIVE diatomics in period two (from left to right) are the "feminine-shaped" diagrams (ladies first) and the last three O2, F2, and Ne2 are the "masculine-shaped" diagrams. Know how to predict bond order, bond length, bond strength/BDE, para or diamagnetism from the diagrams of these diatomic molecules OR ions. Here is a great site for pictures and review of MO Theory:
http://www.chem.latech.edu/~upali/chem281/281GRCc3.htm
Here's another good site that walks you through most of the bonding subtopics with nice graphics:
http://highered.mcgraw-hill.com/sites/0073656011/student_view0/chapter10/essential_study_partner.html
The text sections 10.5 and 10.6 gets into MO Theory (the answer to those sections' questions are posted now) and there is the Bonding II study guide that has MO theory and questions.
# posted by C @ 7:13 PM 
