Chemblog!

Our next exam, the first exam of the second quarter, will cover unit objectives that were posted on 10/29/06 EXCEPT for the last 5 objectives, the Periodicity objectives, which we haven't covered yet. Naturally, the class notes/examples should be the initial source for review. For explanations, be prepared to give detailed LABELED DRAWINGS/DIAGRAMS with accompanying explanations and examples, of

1. The Photoelectric effect and its use of the Planck equation
2. The Bohr Model of the Atom and its relation to the absorption and emission of quanta of energy.
3. The Quantum/Wave Mechanical Model of the Atom and its relation to the absorption/emission of quanta/photons; the relation of matter waves and the Heisenberg Uncertainty Principle to the development of the QM Model, specifically to the concept of "orbitals".
4. The exceptions to the Aufbau Principle i.e. Cr, Cu, Mo,and Ag.

For non-quantum review: expect a thermo problem that involves stoichiometry, calorimetry, and knowing the difference between enthalpy of formation vs. enthalpy of reaction. I've decided against another gas unit problem; sorry, we can only cover so much per test.
Another two test tips:
as we did in class, before you crunch numbers into a formula, write out EXPLICITLY (not just the symbols of the formula) what the formula is and how the variables relate to each other; for example, in the photoelectric effect problem, we wrote, "kinetic energy of the ejected electron = energy of the ABSORBED photon - energy required for the electron to overcome its attraction to the proton(s) in the nucleus"
This way, you'll place the measurements properly and you'll walk yourself through the problem.
ALSO, EXPLICITLY label your units. THE most frequent mess-up on the last test (and most tests) is to have a unit such as kJ per mol WITHOUT labeling what the mol IS!! There may be a HUGE difference between kJ per mol of REACTION and kJ per mol of whatever compound is in the reaction.
Also, it will be advantageous in most problems that have unit changes to work in Joules and kg because a Joule is a kg m^2 s^-2. To go from kJ to J, cross out the letter "k" in kJ and replace the letter with x 10^3 because that is literally what kilo means: 10^3.
On the past exams, students totally messed up and confused MATTER waves (for which you can ONLY use the deBroglie equation: wavelength of the "matter" = Planck's constant divided by the momentum of the matter-particle.) with electromagnetic radiation. ONLY PHOTONS can EVER travel at "c", the speed of light. All matter waves travel at less than the speed of light. Former classes were also unable to correctly do a "work function" photoelectric effect problem- I don't know. YOU all did one or two of them in class without a problem (it seemed). Some past students had trouble following the golden advice that they should draw and extensively label the drawing of the phenomena that they are about to explain. THEN, they should REFER to specific things in their drawing throughout the explanation. Instead, they thought that writing random facts qualified as an explanation. Untrue. Double untrue.