Write a short reaction to it (no more than two paragraphs). Can be either what you found interesting, something that you learned, your opinion on the topics being discussed, or how you agree/disagree with what was written.9475-msk
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Neil Bartlett and the
Reactive Noble Gases
May 23, 2006
A MERICAN C HEMICAL S OCIETY
S C I E N C E T H AT M AT T E R S
C ANADIAN S OCIETY
FOR C HEMISTRY
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“I think I identified at times with the inert gases, and at other times
anthropomorphized them, imagining them lonely, cut off, yearning to bond.
Was bonding, bonding with other elements, absolutely impossible for them?”
noble gases
—Oliver Sacks, Uncle Tungsten (New York: Alfred A. Knopf, 2001), p. 202, fn. 8.
Forbidden union
Scientists had always believed that
noble gases, also known as inert or rare
gases, were chemically unable to react.
Helium, neon, argon, krypton, xenon,
and radon (all gases at room temperature) were viewed as the “loners” of the
Periodic Table. Their inertness became
a basic tenet of chemistry, published in
textbooks and taught in classrooms
throughout the world.
Conventional scientific wisdom
held that the noble gas elements could
not form compounds because their
electronic structure was extremely
stable. For all except helium, the
maximum capacity of the outer
electron shell of the noble gas atom is
eight electrons. For helium, that limit
is just two electrons. These electron
arrangements are especially stable,
leaving the noble gases without a
tendency to gain or loose electrons.
This led chemists to think of them as
totally unreactive.
A few chemists questioned the
absolute inertness of the noble gases.
Among those scientists were Walter
Kossel in 1916 and Nobel-prize winning chemist Linus Pauling in 1933.
They predicted that highly reactive
atoms such as fluorine might form
compounds with xenon, the heaviest
of the noble elements and whose electrons, they observed, were not as tightly
bound as those of the lighter gases.
Mysterious compound
In 1961 Neil Bartlett was teaching
chemistry at the University of British
Columbia in Vancouver, Canada. Some
years earlier, while experimenting with
fluorine and platinum, he had accidentally produced a deep-red solid whose
exact chemical composition remained a
mystery. With the assistance of his
graduate student Derek Lohmann, he
vigorously pursued the identity of the
red solid. After much research they
eventually established that the known
gaseous fluoride, platinum hexafluoride
(PtF6), had reacted with some oxygen
impurity to produce the red solid. The
same solid, which he and Lohman subsequently identified as O2+PtF6–, was
easily obtained by simply mixing the
two gases.
What was most unusual about this
compound was that it contained oxygen
in the form of positively charged ions,
although oxygen usually has a net
negative charge. Oxygen normally pulls
electrons from other atoms and is thus
called an oxidizing agent or oxidant.
But Bartlett believed that, in this case,
the PtF6 component was a more powerful oxidizing agent than even oxygen
and was extracting electrons from
oxygen, leaving oxygen with a net
positive charge. Even though PtF6 was
first prepared some years earlier by
container and xenon — a colorless gas
— in an adjoining container, separated
by a seal. Here is his recollection of
the ensuing experiment, which he
conducted alone in his laboratory:
Because my co-workers at that time
(March 23, 1962) were still not
sufficiently experienced to help me with
the glassblowing and the preparation
and purification of PtF6 [platinum
hexafluoride] necessary for the
experiment, I was not ready to carry it
out until about 7 p.m. on that Friday.
When I broke the seal between the red
PtF6 gas and the colorless xenon gas,
there was an immediate interaction,
causing an orange-yellow solid to
precipitate. At once I tried to find
someone with whom to share the
exciting finding, but it appeared that
everyone had left for dinner!
—Neil Bartlett, “Forty Years of Fluorine
Chemistry” in Fluorine Chemistry at the
Millennium, ed. R.E. Banks; (Amsterdam:
Elsevier Science, 2000), p. 39.
researchers at Argonne National
Laboratory, its oxidizing power had
not been recognized until Bartlett’s
research. It was this development that
led Bartlett to theorize that if PtF6
could oxidize oxygen, then it might also
be able to achieve the “impossible” task
of oxidizing xenon, whose ionization
potential (energy required to remove
an electron) was very similar to that
of oxygen.
Simple experiment
In March of 1962, Bartlett concocted
a simple experiment to test his hypothesis. He set up a glass apparatus containing PtF6 — a red gas — in one
The reaction took place at room temperature “in the twinkling of an eye”
and was “extraordinarily exhilarating,”
recalls Bartlett. He was certain that the
orange-yellow solid was the world’s first
noble gas compound. But convincing
others would prove somewhat difficult.
The prevailing attitude was that no
scientist could violate one of the basic
tenets of chemistry: the inertness of
noble gases. Bartlett insisted that he
had, to the disbelief of some of his
colleagues! The proof was in the new
compound he had made. That orangeyellow solid was subsequently identified
in laboratory studies as xenon hexafluoroplatinate (XePtF6), the world’s first
noble gas compound.
Within months, other chemists
successfully repeated the experiment.
Although the intricate chemical details
behind the reaction would take years to
clarify and the formula of the colorful
solid was later modified as [XeF]+[PtF5]–,
the significance of the experiment
remained clear. Spurred by Bartlett’s
success, other scientists soon began to
make new compounds from xenon and
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I N T E R N A T I O N A L
H I S T O R I C
later, radon and krypton. With Bartlett’s
simple experiment, the old “law” of the
unreactivity of the noble gases had been
vanquished. The new field of noble gas
chemistry, with its exciting possibilities,
had been launched.
Powerful tool
Bartlett’s experiment opened the
door to a better understanding of the
oxidation states of atoms and their
possible reactions. Today, noble gas
chemistry has become a powerful tool
for developing new compounds with
useful properties. “The important
aspect of my discovery,” Bartlett says,
“was to draw attention to fundamental
chemical considerations — especially
that quantitative energy differences are
important when considering variations
in the chemistry of the elements in a
Periodic Table framework.”
Bartlett estimates that more than
C H E M I C A L
L A N D M A R K
100 noble gas compounds are known
today. These fragile compounds are
energy rich: they tend to be extremely
unstable and therefore highly reactive.
More are being discovered every year.
In 2002, researchers at the University
of Helsinki in Finland reported the
formation of the first and only known
argon compound (produced at extremely
low temperatures). Of the six known
noble gases, only helium and neon
have not formed compounds to date.
Noble gas compounds have already
made an impact on our daily lives.
XeF2 has been used to convert uracil
to 5-fluorouracil, one of the first
anti-tumor agents. The reactivity of
radon means that it can be chemically
scrubbed from the air in uranium mines
and other mines. Excimer lasers use
compounds of argon, krypton, or xenon
to produce precise beams of ultraviolet
light (when electrically stimulated)
that are used to perform eye surgery
for vision repair.
Compounds of the gases are poised to
play an even bigger role in the future.
Researchers recently succeeded in combining noble gases with hydrocarbons,
a development that could lead to new
and better synthetic approaches to
some organic materials. Noble gas
compounds also show promise as green
chemistry reagents that allow for more
environmentally-friendly manufacturing
processes. Bartlett believes even the
highly fragile compounds being
produced in Helsinki will provide
benefits as yet unforeseen. All trace
their legacy back to the pivotal
moment in a chemistry lab at the
University of British Columbia, when
a clever young scientist turned conventional wisdom upside down with the
help of a memorable experiment and
changed the face of chemistry forever.
Beginnings
Neil Bartlett was born September 15, 1932, in
Newcastle-upon-Tyne, United Kingdom. One of his
earliest, formative memories was of a laboratory
experiment he conducted in a grammar school class as
a twelve-year-old. In the experiment, he mixed a solution
of aqueous ammonia (colorless) with copper sulfate
(blue) in water, causing a reaction which would eventually
produce “beautiful, well-formed crystals.” From that
moment “I was hooked,” writes Bartlett, who yearned to
know why the transformation took place. He could not
have known that the event would vaguely foreshadow
his famous experiment decades later in which he
produced the world’s first noble gas compound
following a similarly stunning chemical reaction.
He began to immerse himself in chemistry to the
extent that he built his own makeshift laboratory in his
parent’s home, complete with flasks and beakers and
chemicals he purchased at a local supply store. That
curiosity carried over into academic success and eventually earned him a scholarship for his undergraduate
education.
Bartlett attended King’s College in Durham (U.K.),
where he received his Bachelor of Science degree in
1954 and his doctorate in 1958. That year Bartlett was
appointed a lecturer in chemistry at the University of
British Columbia, where he remained until 1966,
eventually reaching the rank of full professor. In 1966
he became a professor of chemistry at Princeton
University while also
serving as a member of
the research staff at Bell
Laboratories. In 1969, he
joined the University of
California, Berkeley, as a
professor of chemistry,
retiring in 1993. From 1969
to 1999 he also served as
a scientist at the Lawrence
Berkeley National
Laboratory. Bartlett
became a naturalized U.S. citizen in 2000.
Bartlett’s fame goes beyond the inert gas research to
include the general field of fluorine chemistry. He holds
a special interest in the stabilization of unusually high
oxidation states of elements and applying these states
to advance chemistry. Bartlett is also known for his
contributions toward understanding thermodynamic,
structural, and bonding considerations of chemical
reactions. He helped develop novel synthetic approaches,
including a low-temperature route to thermodynamically
unstable binary fluorides, including NiF4 and AgF3.
He discovered and characterized many new fluorine
compounds and also produced many new metallic
graphite compounds, including some that show
promise as powerful battery materials.
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The American Chemical Society designated the research of Neil Bartlett on the
noble gases as an International Historic Chemical Landmark on May 23, 2006.
The commemorative plaque at the University of British Columbia in Vancouver
reads:
In this building in 1962 Neil Bartlett demonstrated the first reaction of a noble gas.
The noble gas family of elements – helium, neon, argon, krypton, xenon, and radon –
had previously been regarded as inert. By combining xenon with a platinum fluoride,
Bartlett created the first noble gas compound. This reaction began the field of noble gas
chemistry, which became fundamental to the scientific understanding of the chemical
bond. Noble gas compounds have helped create anti-tumor agents and have been used
in lasers.
About the National Historic Chemical Landmarks Program
The American Chemical Society, the world’s largest scientific society with more
than 158,000 members, has designated landmarks in the history of chemistry
since 1993. The process begins at the local level. Members identify milestones in
their cities or regions, document their importance, and nominate them for landmark designation. In addition, the Society designates international landmarks in
conjunction with other national societies. In either case, an international
committee of chemists, chemical engineers, museum curators, and historians
evaluates each nomination. For more information, please call the Office of
Communications at 202-872-6274 or 800-227-5558, e-mail us at nhclp@acs.org,
or visit our web site: www.chemistry.org/landmarks.
A nonprofit organization, the American Chemical Society publishes scientific
journals and databases, convenes major research conferences, and provides educational, science policy, and career programs in chemistry. Its main offices are in
Washington, DC, and Columbus, Ohio.
American Chemical Society
E. Ann Nalley, President
Catherine T. Hunt, President-elect
William F. Carroll, Jr., Immediate Past President
James D. Burke, Chair, Board of Directors
The Chemical Institute of Canada
Bernard West, MCIC, Chair
Catherine Cardy, MCIC, Vice-Chair
Pudupadi (Sundar) Sundararajan, FCIC, Past
Chair
Roland Andersson, MCIC, Executive Director
Canadian Society for Chemistry
Yves Deslandes, FCIC, President
David W. Schwass, MCIC, Vice-President
Stan Brown, FCIC, Past President
University of British Columbia Organizing
Committee
William R. Cullen, Chemistry, UBC
Robert C. Thompson, Chemistry, UBC
Alan Storr, Chemistry, UBC
Sheri Harbour, Chemistry, UBC
Elizabeth Varty, Chemistry, UBC
Eilis Courtney, Ceremonies, UBC
Danny Leznoff, Chemistry, Simon Fraser
University
American Chemical Society Committee on
National Historic Chemical Landmarks
Paul S. Anderson, Chair, Bristol-Myers Squibb
Pharma Company, Retired
Mary Ellen Bowden, Chemical Heritage
Foundation
D. H. Michael Bowen, Consultant
Leon Gortler, Brooklyn College
Arthur Greenberg, University of New Hampshire
Janan Hayes, Merced College
Seymour Mauskopf, Duke University
Paul R. Jones, University of Michigan
Heinz Roth, Rutgers University
John B. Sharkey, Pace University
John K. Smith, Lehigh University
Kathryn Steen, Drexel University
Isiah Warner, Louisiana State University
Edel Wasserman, DuPont
Frankie Wood-Black, ConocoPhillips
Acknowledgments:
Photo credits: The University of British Columbia
Written by Mark T. Sampson
The author is indebted to the assistance of Neil Bartlett, who shared his recollections of his work on
the noble gases, and William Cullen, who along with Dr. Bartlett read a draft version of this brochure.
He would also like to thank Edel Wasserman and Paul Jones of the National Historic Chemical
Landmarks Committee and Judah Ginsberg, manager of the National Historic Chemical Landmarks
Program, for also reading drafts of this document. Needless to say, any remaining errors are the
author’s alone.
Designed by MSK Partners, Hunt Valley, Maryland
© 2006 American Chemical Society
American Chemical Society
Office of Communications
National Historic Chemical Landmarks Program
1155 Sixteenth Street, NW
Washington, DC 20036
292-872-6274
800-227-5558
www.chemistry.org/landmarks
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