Helium is the most chemically inert element and does not form chemical bonds with any other substance under normal conditions.

Helium is the second element on the periodic table and the first of the noble gases. Its atomic structure consists of two protons and two electrons, which completely fill its 1s orbital. This closed-shell configuration gives helium the highest ionization energy of any element.Because its electron shell is complete, helium has no chemical drive to gain, lose, or share electrons. This makes it the least reactive element known to science. While researchers at institutions including Utah State University have used extreme pressure to force helium into temporary compounds like Na2He, these do not involve traditional chemical bonding and cannot exist under standard Earth conditions.Helium was first detected in 1868 when astronomers Pierre Janssen and Norman Lockyer observed a yellow spectral line in the Sun's atmosphere during a solar eclipse that did not match any known element. It was not isolated on Earth until 1895, when chemist Sir William Ramsay extracted it from the uranium mineral cleveite.Today, helium's inert nature is essential for high-tech industries. It serves as a shielding gas in arc welding and in semiconductor chip manufacturing to prevent unwanted chemical reactions. Its non-combustible stability also contrasts sharply with hydrogen, which was infamously demonstrated during the Hindenburg disaster of 1937.