Part IV
Common Misconceptions (Part II)
3. Radiometers (hollow glass globes with a free-moving vane inside)
prove that photons of light have mass.
Indeed, when a light shines on the vane, it rotates nicely. Actually, there is
a small amount of air in the bulb. Air molecules on the black side of the vane’s
projections warm up more quickly than those on the shiny side. The warmed
gas molecules move faster, pushing against the vane, so it moves.
4. An orbital is the same as an orbit.
Orbits (associated with the planetary Bohr atom model) specify fixed trajectories
for electron movement. An orbital, representing a three-dimensional region
within which one or two electrons can be found, provides no information
regarding specific electron movement.
5. There is an edge, or boundary, to an atom.
Atoms and orbitals have no hard edges. Instead, the contour of the orbital,
as we show it in pictures and models, corresponds to the space of highest
probability for electron location.
6. Air exists between particles (protons, neutrons, and electrons) in atoms.
There is no matter, air or otherwise, between atomic particles, since they are
the matter.
7. The electromagnetic spectrum extends from red to violet light.
Light is the portion of the electromagnetic spectrum visible to the human
eye, but the entire spectrum includes X-rays, radio waves, infrared radiation,
and ultraviolet radiation, as well.
History: On the Human Side.
1. Dmitri Mendeleev (1834 - 1907)
During the mid-1860s, Mendeleev was stimulated by the abolition of serfdom
in Russia and began concerning himself with the practical problems facing his
nation. In 1865 he held a series of lectures at the Free Economic Society on
experimental agriculture, the cooperative production of cheese, and techniques
for agricultural fertilization. Beginning in 1867, Mendeleev conducted research
on the relation and organization of elements. He established correct atomic
weights and arranged the elements in a periodic chart that left blanks for
unknown elements (such as helium, neon, argon, gallium, and germanium,
which were discovered later). The discovery of gallium in 1875 and germanium
in 1886, both of which showed properties predicted by the model, resulted in
broad acceptance of Mendeleev’s periodic table by the scientific community.
2. Max Planck (1858 - 1947)
While a student at the University of Munich, Planck carried out his only
laboratory experiments, such as on osmosis of gases. All of his subsequent work
was in the area of theoretical physics/chemistry. During the 1890s he began
doing research in electrodynamics, and he soon became interested in heat and
black body radiation. In 1899 he completed a derivation of the special distribution
law for heat radiation and examined the difference between absorbed and
emitted energy of bodies. The equations he published formed the basis of the
radiation formulas that describe the quanta (packets of energy) emitted by heated
bodies. Planck was awarded the Nobel Prize in physics in 1918 and continues to
be known as the founder of quantum theory. In the later years of his life, Planck
began writing on the history and philosophy of science and religion. He examined
the divisions between theoretical and applied physics and the role of religion
and science in waging a timeless battle against skepticism and superstition.
3. Albert Einstein (1879 - 1955)
Einstein’s dissertation entitled A New Determination of Molecular
Dimensions revolutionized chemistry and physics by hypothesizing that
light should be considered a collection of independent particles of energy,
called light quanta. The wave theory of light no longer accounted for the
experimental results of blackbody radiation. Einstein’s research showed
that the energy (E) of particles was proportional to the frequency (n) of the
radiation: E=hn. This formula accounted for the properties of fluorescence as
well as the photoelectric effect. In 1907, as a result of further research in this
field, he formulated the famous equation E = mc 2 , which formed the foundation
of the relativity theory and much of 20th century physics. Once this ground-breaking
work was recognized, Einstein was offered a variety of prestigious
positions before moving to Berlin in 1914 as a member of the Prussian Academy
of Sciences, where he had colleagues such as Max Planck and Erwin Schrödinger.
During WWI, Einstein’s research culminated in the general theory of relativity.
Once the term relativity had become a household word, Einstein used his
international position to advocate pacifism. When Hitler came to power in 1933,
Einstein resigned his position in the Berlin Academy of Sciences and moved to
Princeton, New Jersey to work at the Institute for Advanced Study. He
remained there for the remainder of his life, becoming a U.S. citizen in 1940.
Upon recognizing the devastating results of the atomic bomb Einstein, devoted
much of his energy to pacifism and the establishment of the United Nations.
4. Werner Heisenberg (1901 - 1976)
In 1924 Heisenberg went to the Institute for Theoretical Physics in Copenhagen
to study under Niels Bohr who had developed the planetary model of the
atom. According to this model, electrons move in well-defined orbits around
the nucleus. However, by 1925 this theory was no longer reconcilable with
experimental evidence, and the quantum mechanical model was beginning
to evolve. Influenced by Einstein’s work on relativity, Heisenberg began
using variables to represent various observable quantum conditions. His
experiments on atomic and molecular spectra, ferromagnetic phenomena,
and electromagnetism led him in 1929 to state his famous uncertainty
principle. This principle describes a fundamental limitation of modern
physicsone cannot determine with accuracy both the momentum and
position of a particle at the same time. After WWII he organized and became
director of the renowned Max Planck Institute for Physics and Astrophysics
in Göttingen and moved to Munich in 1958 when the Institute relocated there.
5. Niels Bohr (1885 - 1962)
Niels Bohr and Erwin Schrödinger played important roles in developing
theories on atomic structure. Most textbooks document their achievements.
1. Mnemonic aid to recall the order of orbitals in order of increasing energy:
Some People Don’t Forget.
2. Sign on bumper stickers:
a. Heisenberg may have slept here.
b. Wave if you’ve met Schrödinger.
c. Be discreteuse quanta.
3. Student responses on exams:
a. Atoms can expand and travel.
b. An atom is a discrete part of a particle.
c. Atoms are composed of exceedingly minute particles called elements.
4. IONS MINE
We are all familiar with J. J. Thomson’s reputation as a physicist but few
recognize his talent for song writing. This song, with his lyrics, is to be sung
to the tune of Darling Clementine.
1. In the dusty lab’ratory,
’Mid the coils and wax and twine,
There the atoms in their glory,
Ionize and recombine.
Chorus: Oh my darlings! Oh my darlings!
Oh my darling ions mine!
You are lost and gone forever
When just once you recombine!
2. In a tube quite electrodeless,
They discharge around a line,
And the glow they leave behind them
Is quite corking for a time.
3. And with quite a small expansion,
1.8 or 1.9,
You can get a cloud delightful,
Which explains both snow and rain.
4. In the weird magnetic circuit
See how lovingly they twine,
As each ion describes a spiral
Round its own magnetic line.
5. Ultra-violet radiation
From the arc of glowing lime,
Soon discharges a conductor
If it’s charged with minus sign.
6. Alpha rays from radium bromide
Cause a zinc-blende screen to shine,
Set it glowing, clearly showing
Scintillations all the time.
7. Radium bromide emanation,
Rutherford did first divine,
Turns to helium, then Sir William
Got the spectrum every line.
[Chem 13 News/March 1981/p. 3]
5. Tom Weller, Science Made Stupid, Houghton-Mifflin Co., Boston, 1985, pp. 23,
25,75. This humorous paperback pokes fun at atomic theory, dinosaurs,
evolution, and the universe in general.
6. Word Search (see Appendix for master copy)
Words about the concepts in this module can be obtained from the clues
given. Find these words in the block of letters:
1. Difference in the mass number and the number of protons is equal to the
number of ____.
2. Region of space where there is a high probability of finding an electron.
3. Quantum number that identifies the shell where the electron can be found.
4. Acronym for the order of colors in the visible spectrum.
5. Where protons and neutrons are found.
6. Atoms with the same number of protons but different numbers of neutrons.
7. Having only discrete values possible.
8. Distance between successive peaks in a wave.
9. He stated that all orbitals of equal energy are first occupied by single
electrons before any orbital is doubly occupied.
10. Number of protons in an atom’s nucleus is symbolized by this letter.
Answers: 1. NEUTRONS 2. ORBITAL 3. PRINCIPAL 4. ROYGBIV
5. NUCLEUS 6. ISOTOPES 7. QUANTIZED 8. WAVELENGTH 9. HUND
10. Z
7. See cartoons at end of module.
Media:
1. CHEM Study Film, Hydrogen As Viewed by Quantum Mechanics, Advanced
Version. Available from Ward’s Natural Scientific, Inc., P.O. Box 92912,
Rochester, NY 14692-9978. (800) 962-2660
2. Spectrum wall chart (available from Fisher Scientific Co., Educational
Materials Division, 4901 LeMoyne Street, Chicago, IL 60651), with line
spectra of many elements. This can be used to identify the wavelengths of
lines observed in discharge tubes.
3. Electron Configuration film from EME Corporation, Old Mill Plain Road,
Danbury, CT 06811.
4. Software published byJCE: Software, a publication of the Journal of Chemical
Education, Department of Chemistry, University of Wisconsin-Madison,
1101 University Avenue. Madison, Wl 53706-1396: (608) 262-5153 (voice) or
(608) 262-0381 (FAX).
a. Rutherford, by Robert Rittenhouse, Vol. V B, No. 2, for IBM PS/2, PC-compatible
computers.
b. Animated Demonstrations. by Philip Pavlik. Vol. V B, No. 2, for IBM PS/
2. PC-compatible computers.
c. Hydrogen Atom Orbitals, by Michael Liebl, Vol. III A, No. 2, for the Apple
II computer.
d. Atomic Spectroscopy, by Philip Pavlik, Robert Rittenhouse, Martin Rose
and William F. Coleman, Vol. V N, No. 1, for IBM PS/2, PC-compatible
computers.
e. Alpha Scatter, by Robert Rittenhouse. One of the programs in The One-Computer
Classroom, Vol. I A, No. 1 for the Apple II computer.
5. Software published by Project SERAPHIM, Department of Chemistry,
University of Wisconsin-Madison, 1101 University Avenue. Madison, Wl
53706-1396: (608) 263-2837 (voice) or (608) 262-0381 (FAX).
a. For the Apple II computer: AP 204
b. For the Apple II computer running on ProDOS: AR 201, AR 202
c. For IBM PCs and PC-compatibles: PC 2401
6. Videodiscs published by JCE: Software, a publication of the Journal of
Chemical Education, Department of Chemistry, University of Wisconsin-Madison,
1101 University Avenue. Madison, Wl 53706-1396: (608) 262-5153
(voice) or (608) 262-0381 (FAX).
a. The Rutherford Experiment, a chapter on The World of Chemistry: Selected
Demonstrations and Animations: Disc I (double sided, 60 min.), Special
Issue 3.
b. Electron Clouds and The Aufbau Principle, two chapters on The World
of Chemistry: Selected Demonstrations and Animations: Disc II (double
sided, 60 min.), Special Issue 4.
7. Chemical Bonding and Atomic Structure, 23 min. video available from
Coronet/NTI Film and Video, 108 Wilmot Road, Deerfield, IL 60015; (800)
621-2131; (708) 940-3640 (FAX).
Diffraction gratings (available from Edmund Scientific, Central Scientific, or Sargent-Welch
Scientific Company)
H 2 , He, Ne, Hg gas discharge (spectrum) tubes
Power supply for tubes, or Tesla coil
Hand-held spectroscopes (available from Central Scientific)
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