Exam 3 - Bonding Theories and IMFs

Wed 10/26 7-9pm

What the Student Brings to Exams

• official UT ID card (with your picture and name on it)
• a simple scientific calculator (not a graphing calculator)
• NO calculator allowed for exam 3
• a pencil(s) and eraser
• memorized formulas in your head - not on paper or anything else
• nothing else is allowed

What we provide for the Exams

• A printed copy of the exam (every exam has a unique version number on it).
• An answer sheet for the exam. This is a bubblesheet for your answers.
• An exam cover page that has ALL needed conversion factors and data. No formulas will be given.
• A periodic table of the elements with symbols, atomic number, and atomic weights.

What Formulas the Student Should Memorize

No Calculations, No Calculators

Formula - Coulomb's Law

force (ionic bonds): \(\displaystyle F \propto {q_1q_2\over r^2}\)

Energies of Various Interactions

ion-ion: \(\displaystyle E_p\propto -{q_1q_2\over r}\)

ion-dipole: \(\displaystyle E_p\propto -{|q|\mu\over r^2}\)

dipole-dipole: \(\displaystyle E_p\propto -{\mu_1\mu_2\over r^3}\)

dispersion: \(\displaystyle E_p\propto -{\alpha_1\alpha_2\over r^6}\)

NOTE: Although there are no calculations on the exam, these formulas will help you further understand the differences in the various interactions between molecules and ions.

These 2 Helpsheets are exactly that... "helpful"

VSEPR Geometries & VB Hybrids

Intermolecular Forces

What we provide on the exam cover page

Really nothing to provide on this exam.

Remember that all the bonding and shapes really require no data to figure them out. You simply apply the correct theory to the problem (VSEPR, VB, or MO theories). Plus, any polarity is handled by knowing the overall trends in electronegativity on the periodic table. Knowing your periodic trends will aid you greatly in figuring out which molecular or ionic interaction is greater than another.

Learning Outcomes for Bonding

Students will be able to...

1. Identify metals and non-metals, and predict the types of compounds (ionic/covalent) that will form from different elements.
2. Distinguish between molecules, ions, and atoms.
3. Predict the anion or cation that a main-group element is likely to form.
4. Relate Coulomb’s law to ionic radii, ionic charge, and lattice energy.
5. Describe the distance dependence of the potential energy of a covalent bond.
6. Predict and explain relative bond strength and lengths in a compound.
7. Name and write formulas for covalent compounds.
8. Interpret line drawings of chemical compounds with implicit hydrogens, carbons, and lone pairs.
9. Rank the polarity of covalent bonds based on relative electronegativity.
10. Define dipole moment and identify polar bonds.
11. Draw the best Lewis structure (including any resonance structures) for a molecule or polyatomic ion.
12. Apply formal charges to structures and use them to predict the most likely structure.
13. Recognize and apply exceptions to the octet rule.
14. Apply the VSEPR model to determine a molecule's electronic and molecular geometry based on its Lewis dot structure.
15. Assess if a molecule is polar based on polar bonds and its molecular geometry.
16. Identify the orbital hybridization for any atom in a given molecule using the VB model.
17. Describe the type of bond (e.g. sigma, pi) and the atomic orbitals that are associated with the bond using the VB model.
18. Differentiate between localized and delocalized electrons within a structure.
19. Diagram orbital hybridization using orbital notation.
20. Recognize that Molecular Orbital (MO) theory is used to determine the energy of the electron in a molecule as well as its geometry.
21. Differentiate between constructive interference and destructive interference of atomic orbitals.
22. Construct and fully interpret a MO diagram, including identifying the bond order, the lowest energy electronic excitation energy (HOMO-LUMO gap), and the magnetism (paramagnetic or diamagnetic) for a compound.

Learning Outcomes for IMFs

Students will be able to…..

1. Define the three major intermolecular forces (IMFs) that can exist in condensed phases: dipole-dipole, hydrogen bonding, and dispersion.
2. Predict the types of IMFs that a compound can exhibit based on its structure.
3. Using bonding theories and IMFs, predict the chemical and physical properties of organic materials.
4. Explain how size, shape and polarizability affect the magnitude of dispersion forces.
5. Relate the IMFs of a compound to liquid properties such as boiling point, vapor pressure, viscosity, and surface tension.
6. Explain how liquid properties vary with temperature.
7. Fully describe (atomic arrangement/microscopic view) and visually depict the four types of solids (covalent, ionic, metallic, molecular).
8. Summarize how the macroscopic properties of solids (e.g. melting point, hardness, conductivity) can be explained by the microscopic model of solids.
9. Use physical data to deduce the type of bonding within solids.
10. Using a microscopic view, determine if metal alloys will form and compare alloys to their constituent elements.