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In 1907, Ernest Rutherford and Thomas Royds demonstrated that an alpha particle (emitted by radioactive materials) is a helium nucleus.
In 1908, Dutch physicist Heike Kamerlingh Onnes was the first to liquefy helium by cooling the gas to below 1 Kelvin (K).
In 1938, Russian physicist Pyotr Leonidovich Kapitsa discovered that helium-4 has almost no viscosity at temperatures near absolute zero, a phenomenon now called superfluidity. Unlike hydrogen, helium is extremely inert and is the least reactive member of the noble gases.
In 1972, the same phenomenon was observed with helium-3, by American physicists Douglas D. As a result, it is monatomic (consists of single atoms of He) under virtually all conditions.
It is commonly known that helium is used for providing lift for balloons and airships.
It is less water soluble than any other gas known, and its rate of diffusion through solids is three times that of air and around 65 percent that of hydrogen.He tried to solidify it by further reducing the temperature, but he failed because helium does not have a "triple point" temperature where the solid, liquid, and gas phases are in equilibrium with one another.His student, Willem Hendrik Keesom, was the first to solidify helium in 1926, by subjecting it to a pressure of 25 atmospheres. In the periodic table, helium is at the head of the noble gas series in group 18 (former group 8A), and it is placed in period 1, along with hydrogen.Researchers use helium to study materials at very low temperatures, in a field called cryogenics, and in helium dating of radioactive rocks and minerals.Inhaling a small volume of the gas temporarily changes the tonal quality and pitch of one's voice. Helium is the second most abundant element in the known universe, after hydrogen, constituting 23 percent of the elemental mass of the universe.