Chemistry

Discovery of Helium



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Helium is colorless, odorless, and tasteless. It is inert, not reacting with any element, including itself, and so tiny that it is used to find microscopic leaks. How did we ever discover such an elusive element?

Well, first we have to observe something that has not been explained. Astronomers Pierre Janssen and Norman Lockyer were independently observing the spectral lines of a solar eclipse in 1868 and each found an unaccounted yellow spectral line. Lockyer figured that this line was caused by an element hitherto undiscovered on Earth. Naturally it was assumed to be an element of the Sun, thus it was named Helium, a derivation of the name of the Greek sun-god, Helios.

A few decades later William Ramsey - the famous chemist who earlier had discovered the heavier Noble Gases like argon, neon, krypton, and xenon - was shown a mineral called clevite that, upon heating, gave of a gas that initial was thought to be nitrogen. A couple of days later, Ramsey, and independently by chemists Cleve and Langlet, found out the gave a yellow spectral line exactly where Janssen and Lockyer discovered their spectral line. Helium had been discovered on Earth! What's more, it was a member of the Noble Gases - the lightest one.

When the nuclear chemistry of the Sun was figured out in later decades something amazing was discovered: helium happened to be the second most abundant element in the universe! This had to do with a process called nuclear fusion where atoms of elements at the Sun's core join to form atoms of newer heavier elements. Basically, four hydrogen atoms (each with one proton in its nucleus and one orbiting electron) fuse to form two helium atoms (two protons and two neutron in its nucleus and two orbiting electrons) plus some extra particles and energy. Since hhydrogen happens to be the most abundant element in the universe, helium is next on the list. It is amazing we didn't discover helium earlier.

Helium could now be added to the periodic table as a known element, and it had a bright future ahead of it. From cryogenics to supercooling superconductors, from filling balloons to filling airships (to avoid Hindenburg-like disasters), from uses as a noncorrosive gas to underwater breathing equipment, helium has become a mainstay if a variety of industrial applications. It also serves to further edge of human knowledge in areas involving superfluidity and behaviors of substances at temperatures near absolute zero. For a gas that is decidedly, helium definitely has an active role in both science and technology.

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