Tuesday, November 17, 2009
Mon-Day 2
Bio 3/6- we did explicit examples of addition/insertion and deletion mutations. We saw how and why these mutations are called "frameshift" mutations; we first used an analogy to show how a shift in just one letter of a sentence that is read three letters at a time can drastically change the meaning of the sentence just as a shift in just one nucleotide of a gene can drastically change the amino acid sequence that is coded for!
We then did a review worksheet, the answers to which are posted on Blackboard.
AP Chem- we did bond dissociation energy calculations by using the minimum energy per photon required to break a covalent bond in a molecule. Most of these calculations involve an initial conversion from energy required to break one MOLE of bonds to the energy required to break literally ONE bond; we do this because ONE photon is required to break (knock out the electron from between the two nuclei) ONE bond.
We then explained Bohr's interpretation of the emission spectrum of (excited) Hydrogen atoms.
We used this explanation to draw the SPECIFIC allowed energies (and energy transitions) in any hydrogen atom: We took Planck's relationship between the wavelength of electromagnetic radiation and its energy per photon and related that to the light emission spectrum for hydrogen. Bohr developed his model of the atom based on this experimental evidence that proved that electrons could only have certain specific quantities of energy (their "energy levels"). When an electron either absorbs/gains or emits/loses energy, the energy absorbed or emitted MUST BE exactly equal to the energy difference between the "energy levels" through which the electron underwent a TRANSITION. So electrons in hydrogen atoms can only absorb or emit specific energy photons, which is why the emission spectra is not a continuous rainbow of every possible energy photon.The bright lines seen on an emission spectrum MUST be the result of specific energy photons that were emitted due to the electrons in the atoms losing energy as they underwent transitions between two specific energy levels. The larger the energy level transition, the larger the energy of photon emitted.Bohr, using certain physical laws/equations, developed an equation to predict the exact energy levels that exist/are allowed in a hydrogen atom. We used this equation to calculate some possible energy level differences (e.g. n = 6 to n = 3 electron transition) so that we could predict what energy/"color" photons could be emitted and seen on the emission spectrum film.
We then did a review worksheet, the answers to which are posted on Blackboard.
AP Chem- we did bond dissociation energy calculations by using the minimum energy per photon required to break a covalent bond in a molecule. Most of these calculations involve an initial conversion from energy required to break one MOLE of bonds to the energy required to break literally ONE bond; we do this because ONE photon is required to break (knock out the electron from between the two nuclei) ONE bond.
We then explained Bohr's interpretation of the emission spectrum of (excited) Hydrogen atoms.
We used this explanation to draw the SPECIFIC allowed energies (and energy transitions) in any hydrogen atom: We took Planck's relationship between the wavelength of electromagnetic radiation and its energy per photon and related that to the light emission spectrum for hydrogen. Bohr developed his model of the atom based on this experimental evidence that proved that electrons could only have certain specific quantities of energy (their "energy levels"). When an electron either absorbs/gains or emits/loses energy, the energy absorbed or emitted MUST BE exactly equal to the energy difference between the "energy levels" through which the electron underwent a TRANSITION. So electrons in hydrogen atoms can only absorb or emit specific energy photons, which is why the emission spectra is not a continuous rainbow of every possible energy photon.The bright lines seen on an emission spectrum MUST be the result of specific energy photons that were emitted due to the electrons in the atoms losing energy as they underwent transitions between two specific energy levels. The larger the energy level transition, the larger the energy of photon emitted.Bohr, using certain physical laws/equations, developed an equation to predict the exact energy levels that exist/are allowed in a hydrogen atom. We used this equation to calculate some possible energy level differences (e.g. n = 6 to n = 3 electron transition) so that we could predict what energy/"color" photons could be emitted and seen on the emission spectrum film.
# posted by C @ 7:45 AM 
