chem 125 lecture 1 9/5/00 projected material this material is for the exclusive use of chem 125...
Post on 20-Dec-2015
215 views
TRANSCRIPT
Chem 125 Lecture 19/5/00
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 categories)
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
9 lectures
Sept 26
9 lect
Oct 19
9 lect
Nov. 12
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 : Ivar McDonald & ? (Mon/Thurs evenings ? )
Teaching Interns: Kathie Huang & Collin May
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 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?
How do you know?
John McBride (age 3)
How do you know?
John McBride (age 29)
Finger Writes
Shows Joshua
Asks question of Class
Class
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?
Munowitz (fall 73)
Munowitz review facts
Budiansky Cover
How do we know?
What are the most importantTOOLS?
G.N. Lewis(1875-1946)
& his
Cubic Octet
Lewis on running board
G. N. Lewis
Octet "Explains" Periodicity, Electron Transfer(1902)
Octet Predicts Shared Pair Bonding
?
shared edge
shared face
G.W. and Robert Robinson (1917)
Partial Valencesto “explain” trivalent and pentavalent N???
Levitator by Martin Simon (UCLA)
Eppur sta fermo
QuickTime™ and a decompressor
are needed to see this picture.
QuickTime™ and a decompressor
are needed to see this picture.
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)
Visualizing Earnshaw - Coulomb's Electrostatics
A positive particle has a local maximum or minimum of energy only at the location of
another charged particle, never in free space.
In systems governed byinverse-square force laws
there can be no local minimum (or maximum)
of potential energy.
Earnshaw's Theorem
The only stationary pointsare saddle points.
"I have ever since regarded [the cubic octet]as representing essentially the arrangement
of electrons in the atom"
G. N. Lewis (1923)
Was Lewis ignorant ofEarnshaw's Theorem?