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Chemistry 125: Lecture 4Sept. 10, 2010
Coping with Earnshaw, Smallness and Scanning
Probe Microscopy Despite Earnshaw’s Theorem, might there actually be shared-electron bonds? Is it possible to confirm
their reality by seeing or feeling them? The spectacle of “clairvoyant” charlatans from the beginning of the
20th Century, who claimed to “see” details of atomic and molecular structure, contrasts with proper bases
for scientific understanding. The molecular scale is not inconceivably small; indeed Newton and Franklin
could perform simple experiments capable of measuring nanometer-scale distances. In the last 25 years
various manifestations of Scanning Probe Microscopy have enabled chemists to “feel” individual
molecules and atoms, but not bonds.For copyright
notice see final page of this filePRELIMINARY
Motivation for the Trajectory of Coulomb’s Work with his Torsion Balance:
Devises an improved suspension for a compass needle.
Studies wire torsion “in order to determine the laws of cohesion and elasticity in metals and in all solid bodies.”
(Engineering; Newton’s “Business of Experimental Philosophy”)
Confirms Hooke’s Law for torsion.
1784
1777
1785-9 Determines 1/r2 Laws for E&M.
Some Resonance Structures for H, C, N, O Isomers
For quantum-calculatedlocal-minimum-energy (valley)
atomic arrangements
H, C, N, O isomersC in middle
H
C NO :: :
H
C NO:
: :
H
C NO::
:
+
_
H
C NO :: :
+ _
bad charge separation(most “electronegative”
atom bears + charge) charge separation
H
C NO:+ _
: :
bad charge separation
H
C N O:
:
:
:
H C N O:
::
+ _
:H C N O:
: +_
+_ H
C NO::
:
:
+_ H
C N O::
:
bad charge
sestet
sestet
bad charge
bad charge
H, C, N, O isomersN in middle
H C N O:
::
+ _:
better charge
sestet
H
C NO ::
:: +
_H
C NO
:
::
:
_
+
H
C NO
:
::
:
_
+
H
C NO
:
:
:
:+
_
sestet
sestet
bad charge bad charge
sestet
sestet
H, C, N, O isomersO in middle
Ring
Open
HC
N
O
:
:
: H
CN
O: :
+: _
H
CN
O: ::
:sestet
bad charge
H, C, N, O isomerscyclic
H
C
N
O:
:
:
+ _
sestet
H
C
N
O
:
:
:
+
_
:bad charge
Unlike O3, lowest energy form can’t even be calculated.
(smoothly downhill to open the ring)
HNCOisomers
HC
N
O
:
:
:
H
C NO :: : H
C NO:
: :
H
C N O::
::
H C N O :
::
+ _
H
C NO ::
:
: +_
H
C NO
:
::
:
_
+
H
CN
O: :
+
: _
HNCOisomers
150
100
50
0
200kc
al/m
ole
H
C N O
H
C NO
H
C NO
H C N O
H
CN
O
H
C NO
H
C NO
HC
N
O
Eca
lc
“I once poured 6 drams of concentrated sulfuric acid upon 50 grains of mercury fulminate. An explosion nearly at the instant of contact was effected; I was wounded severely, and most of my apparatus was destroyed. … I must confess that I shall feel more disposed to prosecute other chemical subjects.
Edward Howard (1800) .
… I must confess that I shall feel more disposed to prosecute other chemical subjects.
References:
Most of these structures and energies were calculated at a very high level of theory as reported in Journal of Chemical Physics, 120, 11586-11599 (2004).
The much less stable structures with O in the middle were calculated using the highest level of theory available in the Spartan 04 package of quantum programs. This program could not find an energy minimum for the cyclic structure with H on oxygen.
Coping with Earnshaw
J.J. Thomson (1856-1940)
Electron (1897) Plum-Pudding Atom
© C
ave
ndi
sh L
abo
ratp
ry,
Cam
brid
ge U
nive
rsity
"[We can] solve the special case where the corpuscles are
confined to a plane."
Thomson's Model of Electron Configuration
"consider the problem as to how 1…2…3…n corpuscles would arrange themselves if placed in a sphere filled with positive electricity of uniform density…"
“distributed in the way most amenable to
mathematical calculation”
in
Thomson, Corpuscular Theory of Matter (1907)
Vortex Lattice Models (Greg Blonder www.genuineideas.com)
"[We can] solve the special case where the corpuscles are
confined to a plane."
Thomson's Model of Electron Configuration
"consider the problem as to how 1…2…3…n corpuscles would arrange themselves if placed in a sphere filled with positive electricity of uniform density…"
"the equilibrium of eight corpuscles at the corners of a cube is unstable."
in
“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 of Earnshaw's Theorem?
“Electric forces between particles which are very close together do not obey the simple law of inverse squares which holds at greater distances.”
G. N. Lewis (1916)
The Electron in Chemistry
J. J. Thomson (1923)
“… if [electron-nuclear attraction] were to vary strictly as the inverse square of the distance we know by Earnshaw's theorem than no stable configuration in which the electrons are at rest or oscillating about positions of equilibrium is possible ...
Couloumbr
cr
c
… then a number of electrons can be in equilibrium about a positive charge without necessarily describing orbits around it.”
I shall assume that the law of force between a positive charge and an electron is expressed by the equation
F =Ee
r2 1
atomic length scale(for distances r smaller than c,
the force changes sign.)
Quantum Mechanics (1926)
Kinetic energy is reformulated to explain electron clouds and produce an "inverted"
plum-pudding atom.
Cubic octets and the ad hoc electrostatic force law soon disappeared from
conventional Chemistry and PhysicsBut shared-pairs and lone-pairs
remained useful tools for discussingstructure and bonding.
Coulomb’s Law is just fine.
Earnshaw:
No structure of minimum energy
forpoint charges
Classical
Despite Earnshaw, might there still be shared-pair bonds
and lone pairs?
How do you know?
By Seeing? Feeling?
Problem:
InconceivablySmall
?
OCCULT CHEMISTRY
A SERIES OF
Clairvoyant Observations on theChemical Elements
BY
ANNIE BESANT, P.T.S.
AND
CHARLES W. LEADBEATER
Reprinted from the Theosophist.
THEOSOPHIST OFFICE, ADYAR, MADRAS, S.
THEOSOPHICAL PUBLISHING SOCIETY, LONDON AND BENARES CITY.
1909 (105 pp.)
1919 (123 pp.)
1951 (400 pp.)
Mrs. AnnieBESANT
P.T.S.(1847-1933)
CuruppumullageJINARAJADASA
P.T.S.(~1877-1953)
"Bishop"Charles WebsterLEADBEATER
(1847 - 1932)
The Occult Chemists (1895-1932)
H O N (1895)18 290 261
HydrogenOxygen“Anu”
Atom Model in Charles Jencks’sGarden of Cosmic Speculation
(1994)
constructed “with several scientists”
Helium72
Lithium127
Iron1008Neon360
Occult Atoms
Neon360
4forbital
e-density
Occult Atoms
Bases for Scientific Belief:
1) Experimental Evidence "cross-examine an assertion"
3) Taste matures with experienceWhy should you believe the professor/text?
2) Logic
Sodium418
Occult Atoms
Na2CO3(1924)
"note that this trian-gular arrangement of O3 has just been deduced by Bragg from his X-ray analysis of Calcite"
OO
O
CNaNa
Benzene(1924)
"each of the three valencies of each Carbon are satisfied by Hydrogen, and the fourth valency, which some have postulated as going to the interior of the molecule, does actually do so."
Cf. Question 6
Benzene “Resonance”
H
H
H
H
H
H
CC
CC
C
CH
H
H
H
H
H
CC
CC
C
C
H
H
H
H
H
H
CC
CC
C
C
(1889)
Clean Slates April, 1923
GiuseppeBruni
(Bologna)
G. N.Lewis
Honor Roll of (mostly) dead chemists
Dedication:
1861 - discovered Thallium
developed Cathode Ray Tube
invented Crookes Radiometer
Sir William CrookesFRS, FTS (1832-1919)
Supplied Li, Cr, Se, Ti, V, B, Be to Leadbeater and Besant (1907)
andThe Society for Psychical
Research
"[Telepathic research] does not yetenlist the interest of the majority
of my scientific brethren."
1913-1916 - President of the Royal Society
1898 - PresidentBritish Assn. for the Advancement of Science
6/18 1023 molecules
molecules / cm
1 cm3 of water, 1/18 mole
Are Molecules Unobservably Small for
“Vulgar Eyes”?
€
1 3×10233 ≈ 3×107
~ 3Å / H2O molecule
105
Lecture Room ~10 m
Hair ~100 mm
Nucleus ~10 fm
Molecule ~1 nm(small atom ~ 0.1 nm = 1 Å)
101
10-4
105
10-9
105
10-14
105
(again)
3/8 10-6 2.54 cm/inch≈ 10-6 cm = 10 nm= 30 "waters" !
Newton Opticks (1717)
p. 369
flatto
flat
62 mm
convex to
flat
Newton’s Rings
~1 mmgap
at rim
1 mm
p. 175
Newton Opticks (1717)
= cos-1(0.29"/(12"51')) = 89.973°
air gap
0.29"
= (1251)(1-sin ) = 7 10-5 inch = 1.8 mm
51'
Simpler Measurementof Smaller Distance
1774
BenjaminFranklin1706-1790
PhilosophicalTransactions
of theRoyal Society
1774
Portrait by Paulze Lavoisier 1783http://moro.imss.fi.it/lavoisier
Benj. Franklin to Wm. Brownrigg (1773)
…I had, when a youth, read and smiled at Pliny's account of a practice among the seamen of his time, to still the waves in a storm by pouring oil into the sea; as well as the use made of oil by the divers... I think that it has been of late too much the mode to slight the learning of the ancients. The learned, too, are apt to slight too much the knowledge of the vulgar.
In 1757, being at sea in a fleet of ninety-six sail bound against Louisbourg, I observed the wakes of two of the ships to be remarkably smooth, while all the others were ruffled by the wind, which blew fresh. Being puzzled with the differing appearance, I at last pointed it out to our captain and asked him the meaning of it. "The cooks," said he, "have I suppose been just emptying their greasy water through the scuppers, which has greased the sides of those ships a little." …
Benj. Franklin to Wm. Brownrigg (1773)
recollecting what I had formerly read in Pliny, I resolved to make some experiment of the effect of oil on water when I should have the opportunity.
Franklin's ExperimentLondon, 1762
Clapham Common
for I had applied it first on the leeward side of the pond where the waves were greatest; and the wind drove my oil back upon the shore. I then went to the windward side where they began to form; and there the oil, though not more than a teaspoonful, produced an instant calm over a space several yards square which spread amazingly and extended itself gradually till it reached the lee side, making all that quarter of the pond, perhaps half an acre, as smooth as a looking glass.
Benj. Franklin to Wm. Brownrigg (1773)
At length being at Clapham, where there is on the common a large pond which I observed one day to be very rough with the wind, I fetched out a cruet of oil and dropped a little of it on the water. I saw it spread itself with surprising swiftness upon the surface; but the effect of smoothing the waves was not produced;
1 tsp ≈ 5 cm3
0.5 acre ≈ 2000 m2 = 2 x 107 cm2
layer thickness ≈ 5 cm3 / 2 x 107 cm2
= 2.5 x 10-7 cm = 2.5 nm = 25 Å
Benj. Franklin to Wm. Brownrigg (1773)
When put on water it spreads instantly many feet round, becoming so thin as to produce the prismatic colours for a considerable space, and beyond them so much thinner as to be invisible except in its effect of smoothing the waves at a much greater distance. It seems as if a mutual repulsion between its particles took place as soon as it touched the water
Are there Electron Pairs?
Scanning Probe Microscopyfor Feeling Individual
Molecules, Atoms, Bonds?
Scanning Tunneling Microscopy (1981)
Heinrich Rohrer
Gerd Binnig
Nobel Prize (1986) © I
BY
by
perm
issi
on
http
://no
belp
rize
.org
http
://no
belp
rize
.org
End of Lecture 4Sept 10, 2010
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