Thursday, October 26, 2006
Evac Day
AP- thanks for racing back from the field...our truncated class turned into a slightly extended class (perhaps I made up the "lost" ten minutes from a certain class last week; still trying to block that out).
We did the ultimate marathon thermo problem...I'm glad we got to do the delta nRT substitution so that we could still calculate delta H even though we initially only had delta E as calculated from the heat released under constant volume conditions...we also further saw the difference between heat of formation and heat of reaction...we even talked about bond angle strain, which you won't hear again until you ace orgo chem in college.
D,G: we dug into the Bohr Model today by looking at the bright-line emission spectrum of hydrogen and relating the spectrum to the energy levels of the electrons in a hydrogen atom. Bohr saw that the electrons must ONLY have SPECIFIC amounts of energy in an atom. He called these electron energies "energy levels" and proposed that electrons could only ABSORB or EMIT quanta of energy EQUAL TO the DIFFERENCE in energy BETWEEN ANY two DIFFERENT principal energy levels in an atom. As an electron LOSES a SPECIFIC amount of energy as it undergoes a TRANSITION from a HIGHER principal energy level to a LOWER principal energy level, that exact amount of LOST energy is EMITTED as a PHOTON (quantum) of light energy.
The video is on the main class website.
E: We further discussed and practiced with the quantum/wave mechanical model of the atom. Worksheets and answers are online for additional practice.
We reviewed a few questions from the last test. One question that I didn't go over involved TWO Hydrogen atoms CHEMICALLY COMBINED. I don't recall ANYBODY getting that simple question right. ANYTHING that is made up of JUST ONE ELEMENT must be called AN ELEMENT! Most people called the two H atoms a MIXTURE!!! Just the word mixture, in English, means two or more DIFFERENT things mixed together. Clearly, two IDENTICAL Hydrogen atoms can't be a mixture.
Use your notes and your orange review book to see pictures that show the difference between an element, a compound, a homogeneous mixture (called a "solution"), and a heterogeneous mixture (YOU are a heterogeneous mixture).
Study for your next test.
I'm in early tomorrow, Day 4.
We did the ultimate marathon thermo problem...I'm glad we got to do the delta nRT substitution so that we could still calculate delta H even though we initially only had delta E as calculated from the heat released under constant volume conditions...we also further saw the difference between heat of formation and heat of reaction...we even talked about bond angle strain, which you won't hear again until you ace orgo chem in college.
D,G: we dug into the Bohr Model today by looking at the bright-line emission spectrum of hydrogen and relating the spectrum to the energy levels of the electrons in a hydrogen atom. Bohr saw that the electrons must ONLY have SPECIFIC amounts of energy in an atom. He called these electron energies "energy levels" and proposed that electrons could only ABSORB or EMIT quanta of energy EQUAL TO the DIFFERENCE in energy BETWEEN ANY two DIFFERENT principal energy levels in an atom. As an electron LOSES a SPECIFIC amount of energy as it undergoes a TRANSITION from a HIGHER principal energy level to a LOWER principal energy level, that exact amount of LOST energy is EMITTED as a PHOTON (quantum) of light energy.
The video is on the main class website.
E: We further discussed and practiced with the quantum/wave mechanical model of the atom. Worksheets and answers are online for additional practice.
We reviewed a few questions from the last test. One question that I didn't go over involved TWO Hydrogen atoms CHEMICALLY COMBINED. I don't recall ANYBODY getting that simple question right. ANYTHING that is made up of JUST ONE ELEMENT must be called AN ELEMENT! Most people called the two H atoms a MIXTURE!!! Just the word mixture, in English, means two or more DIFFERENT things mixed together. Clearly, two IDENTICAL Hydrogen atoms can't be a mixture.
Use your notes and your orange review book to see pictures that show the difference between an element, a compound, a homogeneous mixture (called a "solution"), and a heterogeneous mixture (YOU are a heterogeneous mixture).
Study for your next test.
I'm in early tomorrow, Day 4.
# posted by C @ 8:34 PM 
