Helium is the second most abundant element in the universe. Represented in the periodic table with the symbol He, it is part of Group 18, Period 1, Block s. It has the atomic number 2 and an atomic weight of 4.002602. Helium has the electron configuration of 1s2.
At room temperature, helium is a gas. It is colorless, odorless, tasteless and lighter than air. The melting point of helium is -458 degrees Fahrenheit; this is the lowest melting point of any element. The boiling point is -452 degrees Fahrenheit, which is close to absolute zero. It has high thermal conductivity and low density.
There are eight known helium isotopes -- or atom variants of this chemical element -- as of publication. The most stable of these are helium-3 -- used in nuclear fusion research -- and helium-4, which mostly stems from alpha decay in Earth's crust. In Earth's atmosphere, there are a million helium-4 atoms for every helium-3 atom.
Helium is used in multiple disciplines including cryogenics -- the study of low-temperature production -- and manufacturing. Gas helium is used to make airships float. Helium is also used as a mixture in breathing apparatus for deep-sea divers; this mixture helps prevent high-pressure nervous syndrome. Liquid helium is used in MRI machines to cool the superconducting magnets.