Chemblog!

As I announced in class on Friday, we will have covered enough material by Tuesday to have an exam on Wednesday, Day 1 (Oct. 26). Practice your DRAWINGS, descriptions, and explanations and show them to me (or email them to me) BEFORE the test next week and I will tell you how great they are (or specifically what is wrong with a given part of your answer).
My impression is that all of you understand the Bohr Atomic Model well; you also "get" the photoelectric effect evidence and conclusions (except some still confuse intensity with energy PER photon) and you can relate that to Planck's equation, however, I think that some of you are fearful about the Blackbody Radiation evidence and conclusions.
To try to allay your fears and focus your study, l will reiterate what I said in class: you do NOT have to explain or even understand HOW Planck discovered that light must exist as quanta (particles/packets of specific energy). Do NOT WORRY about that. You do have to relate that graphical data to Planck's equation E = hf ( or E = hc/(wavelength) ), that is,

1.) to see how Planck could tell that a high-frequency/short wavelength quantum (photon) MUST have MORE energy than a low frequency/(long wavelength) quantum...

which involves showing 2.) why few to no x-ray quanta (photons) were emitted when the blackbody was at a low temperature but that some (or more than the number of photons emitted before) x-ray quanta (photons) were emitted when the blackbody was then heated to a higher temperature.

remember, the more total energy that a substance absorbs, the MORE total energy the substance can emit.

Furthermore, the Blackbody Radiation experiment, though it is monumental in its significance to understanding the atom, only has two VERY tiny conclusions:
-light has a particle nature
-the minimum amount of energy of a given type of "light" is a "quantum"/photon (which equals hf)...so, any amount of light energy must be a whole-number multiple of a single quantum of energy (of that particular type of light) e.g. 5 photons of energy of a specific color of orange light has exactly 5 times as much energy as 1 photon of that specific orange light but it is impossible to have half of one quantum of energy of that specific orange light (there are NO fractional photons, only whole particles).
(in fact, the minimum amount of ANY type of energy is a QUANTUM of that form of energy, FYI)