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

Copyright © J. M. McBride 2009. Some rights reserved. Except for cited third-party materials, and those used by visiting speakers, all content is licensed under a Creative Commons License (Attribution-NonCommercial-ShareAlike 3.0).

Use of this content constitutes your acceptance of the noted license and the terms and conditions of use.

Materials from Wikimedia Commons are denoted by the symbol .

Third party materials may be subject to additional intellectual property notices, information, or restrictions. 

The following attribution may be used when reusing material that is not identified as third-party content: J. M. McBride, Chem 125. License: Creative Commons BY-NC-SA 3.0