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Chem 125 Lecture 19/4/02
Projected material
This material is for the exclusive use of Chem 125 students at Yale and may not
be copied or distributed further.
It is not readily understood without reference to notes from the lecture.
Enter on the white card in this order (no need to write the word “Name”, etc.)
Name (pronunciation hints if necessary)
Prefer to be Called (e.g. Jay, not Jethro)
Hometown with zip code
Name of your best science teacher (with subject)
Prospective major(s)
Put comments or questions on back.
Exam Dates
10 lectures
Sept 27
9 lect
Oct 21
9 lect
Nov. 13
10 lect Dec 17
100 pts
100 pts
100 pts
300 pts
Semester grade biased by faithfulness in timely problem set submission
HELP !
Other Chem 125 students!Alumni
Text: Introduction to Organic Chemistry (4th ed) Streitwieser, Heathcock, and Kosower
Lecture Notes (in-class questions)Course web site: www.classes.yale.edu/chem125a
Assigned problems or questions
Instructor : Prof. J. M. McBrideTAs : Roger Cole (Mon/Thurs evenings ? )
Teaching Interns: Diana Mandelker & Josh Dunn
Problems For Friday: 1) Which two class members live nearest you?2) What are the three most common items of advice from course veterans?3) Send as e-mail to [email protected]
For Monday:(Problems from Text - Ch 2: 1,2, 4a-e, 5a-e)1) Are Lewis Structures correct?2) What do they show?
Do not suppose that I was a very deep thinker, or was marked as a precocious person. I was a very lively imaginative person, and could believe in the "Arabian Nights" as easily as in the "Encyclopaedia." But facts were important to me, and saved me. I could trust a fact, and always cross-examined an assertion. So when I questioned Mrs. Marcet's book by such little experiments as I could find means to perform, and found it true to the facts as I could understand them, I felt that I had got hold of an anchor in chemical knowledge, and clung fast to it.
Michael Faraday, 1858
If they say to you science has shown such and such, you might ask, "How does science show it - how did the scientists find out - how, what, where?" Not science has shown, but this experiment, this effect has shown.
When someone says science teaches such and such, he is using the word incorrectly. Science doesn't teach it; experience teaches it.
Learn from science that you must doubt the experts…Science is the belief in the ignorance of experts.
Richard Feynman (to National Science Teachers Assn 1966)
Why cite Feynman?
No.Because he deserves credit for saying something that is true
and saying it very well .
Because he is an expert?
Text p. 16“empirical rules for assessing the relative importance of the resonance structures of molecules and ions.
1. Resonance structures involve no change in the positions of nuclei; only electron distribution is involved.
3. The more important structures are those involving a minimum of charge separation, particularly among atoms of comparable electronegativity. Structures with negative charges assigned to electronegative atoms may also be important.
2. Structures in which all first-row atoms have filled octets are generally important; however, resulting formal charges and electronegativity differences can make appropriate nonoctet structures comparably important.LORE
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Thanks to Prof. André Geim
Frog
In systems governed byinverse-square force laws
there can be no local minimum (or maximum)
of potential energy.
Earnshaw's Theorem(1839)