Michael Rosenthal

(7/2019) This is The International Year of the Periodic Table of the Elements, so I thought it might be interesting to explore the properties of the elements described as The Noble Gases. The Noble Gases were named such because of their low chemical reactivity, which is due to a completed outer shell of electrons. They consist of the elements Helium, Neon, Argon, Krypton, Xenon, and Radon. Because of this completed outer electron shell, the noble gases are not very chemically reactive, and they also have special physical properties. The first chemical compound of a noble gas to be synthesized was Xenon Hexafluoroplatinum, Xe (PtF6), synthesized in 1962. These elements do however serve special purposes, including the use of helium to achieve very low temperature in the laboratory, neon in illumination in signage, argon for producing an inert atmosphere in laboratory environments, krypton in photography, and xenon in propelling spacecraft.

An atom of helium consists of 2 protons and 2 electrons. It is a colorless, tasteless, non-toxic gas, and it is the first Noble Gas, as they are called, in the periodic table of elements. A few of the noble gases are not entirely noble! Xenon and Krypton can form stable chemical compounds. This was first observed in 1868 in the spectrum of the sun. The earliest large scale usage of a noble gas was to fill airships; it was referred to as a lifting gas because of its lighter-than-air quality. The first helium filled airship was the U.S. Navy’s C-7, which flew from Hampton Roads, Virginia, to Bolling Field in Washington, D.C. on December 1, 1921. In 1925 the United States government set up the National Helium Reserve in Amarillo, Texas. As of 2012 The United States National Helium Reserve accounted for 30 % of the world’s helium. The noble gases, as we said, have a completed electron shell and are thus very difficult to get to react to form compounds. Only Xenon and Krypton form stable compounds, and only in quantities of a few milligrams or slightly more. Helium can be liquefied only if cooled to -457.96 degrees Fahrenheit!

I remember when I was growing up seeing helium-filled balloons, the Goodyear Blimps, in the sky (I think they may still be around?), filled from helium tanks. I also remember seeing people inhale helium from helium tanks for amusement and having their voices change in pitch to a very high level. Airships were safe when filled with helium because of its extremely low chemical reactivity and non-combustibility, unlike hydrogen, which is ignitable and highly explosive. The Airship Hindenberg disaster of 1937 in Lakehurst, New Jersey, was illustrative of the dangers of filling an airship with hydrogen. Liquid helium is used in the cooling of supercooling magnets because of its very low temperature.

In 1903 in Dexter, Kansas, an oil drilling operation produced a gas geyser that would not burn. The escaping gas was captured by a geologist and taken to the University of Kansas, where it was found to contain helium. This discovery eventually enabled the United States to become the world’s leading supplier of helium. During World War I the United States Navy sponsored the construction of helium plants to supply barrage balloons with the non-flammable, lighter than air gas. The National Helium Reserve was established to supply military airships in time of war and to supply commercial airships in peacetime. In 1925 the Helium Act banned the export of helium. This is why the German airship Hindenberg was forced to use the highly explosive and flammable hydrogen as its lifting gas.

By 1995 a billion cubic meters of helium gas was collected and put in reserve, but financial issues caused the United States government to eventually phase out the reserve and sell the helium in it. For many years the United States produced more than 90% of the commercially usable helium, but plants in other parts of the world have since taken up the task.

Noble Gas chemistry is still alive and well. In 1962 the chemist Neil Bartlett synthesized the first noble gas compound, Xe(PtF6) by mixing Xenon with platinum hexafluoride. Compounds of the noble gases are not easy to make, because their completed outer electron shell is bonded firmly to the nucleus of the atom, and thus requires extremes such as reactive reagents, low temperature, or high pressures to make these electrons budge from their stable position in the atom. It is a whole different kind of synthetic chemistry!

You can’t pick up a newspaper today, watch television, or roam the Internet without seeing stories about the movement to give women the professional recognition that that had been denied to them in the past. An aspect of that which is relevant to my experience is that of women scientists on chemistry faculties. When I was an undergraduate at Case Western Reserve University in Cleveland in 1957-1961, there were only a few women chemistry majors. In my graduate years at the University of Illinois in 1961-1965, there were a few women students in the chemistry graduate program, and to the credit of that great university, they were treated with respect. However, there was not a single woman on the U of I Chemistry Department faculty at that time…except the Chemistry Librarian!

A recent article in Chemical and Engineering News, the magazine of the American Chemical Society, lists "Women Chemists in Academia for 2016-2017." Progress has been made. A number of the major institutions with PhD graduate programs in chemistry have increased their percentage of women on the faculty. The leader in this survey is Northeastern University in Boston with 32% of its chemistry faculty being women. The University of Illinois in Urbana-Champaign, my graduate alma mater, has 25% women. At the bottom of the list is The University of Southern California with only 8% women. The all-over total among the major universities listed is 20%. To their credit, The American Chemical Society has had a number of women presidents in recent years, including the current president, Dr. Bonnie Charpentier, an industrial scientist who serves as a Senior Vice President at Cytokinetics.

______________________________

We have written previously about the problem due to discarded plastics. The Council of the European Union (EU) enacted a single-use plastic ban on May 21 in Brussels, with the goal of reducing maritime litter. Plastic cotton swab sticks, cutlery, plates, straws, drink stirrers, and sticks for balloons will need to be made of more sustainable materials by 2021. Single-use plastic drink containers will be allowed only if their caps remain attached. Plastic bottles will need to be made of at least 30% recycled plastic by 2030. For products without cheap and easy non-plastic alternatives, such as wet wipes and fishing gear, the focus will be on limiting use. Producers of these products will be obliged to help cover cleanup costs and to promote awareness of litter and waste management options. Individual countries of the EU will have two years to transpose the legislation into their national laws.

Read other articles by Michael Rosenthal