Noble-gas Discovery Garnered 1904 Chemistry Nobel Prize

Every first-year chemistry student knows about them nowadays: those chemically dull elements that occupy the far right column of the periodic table. But it wasn't until the end of the 1800s that the noble gases were discovered and their place in the periodic table was established. For those accomplishments, Sir William Ramsay was awarded the Nobel Prize in Chemistry 100 years ago.

Born in Glasgow in 1852, Ramsay "inherited the taste for chemistry," as he put it in his 1904 Nobel lecture, from both sides of his family. His paternal grandfather was a chemical manufacturer and came from a long line of Scottish dyers. His mother's father was a physician and author of medical textbooks.

As a university student, Ramsay focused on organic chemistry. But during his tenure at the University of Bristol (1882­87) and later at University College London, Ramsay investigated stoichiometry, thermodynamics, properties of gases, and other topics in physical chemistry.

In the early 1890s, Ramsay puzzled over a curious observation made by Lord Rayleigh (John William Strutt). Rayleigh, who was a scientist at the Royal Institution of Great Britain, found that the density of nitrogen collected from air samples always appeared greater than the density of the gas prepared chemically--for example, through decomposition of nitrogen compounds. A related problem had been considered more than 100 years earlier by Henry Cavendish, but was left unsolved. At first, Ramsay and Rayleigh worked on the problem independently. Eventually, they collaborated and communicated regularly, though they continued working in separate laboratories.

The two proposed that the discrepancy in gas densities was due to the presence of a heavier-than-nitrogen component of air, and they devised experiments to search for it. Ramsay separated nitrogen from air and then passed the dried gas through red-hot magnesium, which absorbed the nitrogen and left behind the heavier component. Rayleigh removed nitrogen from air samples by forming nitrogen oxides using electric discharges.

The purified residue was analyzed by physical and chemical means, and its spectrum was measured. The studies proved that air indeed contains a component that--prior to Ramsay and Rayleigh's work--had been unidentified. In August 1894 at a meeting of the British Association, Ramsay and Rayleigh announced the discovery of a new element they named argon--Greek for "lazy" because of its chemical inertness. In the same year that Ramsay won the Nobel Prize in Chemistry, Rayleigh was honored with the prize in physics, in part for his discovery of argon.

While conducting experiments that led to the discovery of argon, Ramsay learned that American scientists had observed unidentified gases evolving from uranium minerals when they were heated in sulfuric acid. He turned his attention to those minerals and others, hoping to find argon compounds. Instead, he discovered terrestrial sources of helium, which until that time had only been known to exist in the sun.

In his Nobel lecture, Ramsay explained that similarities in the properties of helium and argon and analysis of the periodic table led him to conclude that the two elements "belong to the same natural family ... and there must exist at least three other elements of the same class."

Using liquefaction and fractional distillation methods, Ramsay succeeded in isolating from air three new elements in the summer of 1898. He named them krypton ("hidden one"), neon ("new one"), and xenon ("the stranger").