The Space Age Element
Helium, named after Helios the Greek sun god, holds the unique distinction of being the only element discovered in space before Earth. First detected in the sun's spectrum during the 1868 solar eclipse, Helium is the second most abundant element in the universe yet one of the rarest on Earth.
Extraordinary Physical Properties
Helium exhibits remarkable properties that defy common experience. It's the only element that cannot be frozen into a solid at normal pressure - even at absolute zero (-273.15°C), Helium remains liquid unless pressure exceeds 25 atmospheres. At 2.17K, Helium-4 becomes a superfluid with zero viscosity, capable of flowing upward and through molecular-sized pores.
Noble Gas Characteristics
As the first noble gas in the periodic table, Helium is completely chemically inert under all known conditions. Its electron configuration (1s²) represents a completed shell, making it the most stable element. No Helium compounds exist naturally, though exotic Helium hydride ions (HeH⁺) have been created in laboratory conditions.
Isotopic Properties
Helium-4 (⁴He): 99.999863% abundance - produced by alpha decay of radioactive elements
Helium-3 (³He): 0.000137% abundance - extremely rare, potential fusion fuel worth $15,000 per gram