Helium is a chemical element which occurs in great abundance throughout the universe, although it is not as widely distributed on Earth. It typically takes the form of a gas, and it heads up the list of noble gases in the periodic table of elements. Like other noble gases, helium is extremely stable, and it does not readily form compounds with other elements. There are a number of uses for helium, and it is widely considered to be a very useful and valuable element.

The atomic number of helium is two, making it the second lightest element. It is identified on the periodic table with the symbol He, and it is the least reactive of the noble gases. As a result, helium is one of the least reactive elements on Earth. The extreme stability of helium makes it a popular choice for a range of uses in situations where unstable materials are being handled, or where the use of other elements might be dangerous.

The discovery of helium occurred in 1868, when astronomers observed a strange band of light during a solar eclipse. The band of light did not correlate with any known element, and the observers realized that they had identified a new gas, which they called “helium” after the Greek Helios, for “Sun.” Within 30 years, scientists had succeeded in isolating and extracting the gas from the mineral clevite.

Although helium is the second most abundant element in the universe, it can be challenging to find on Earth. It is frequently extracted from natural gas, which can contain helium in concentrations ranging from two to seven percent. The extremely stable, non-reactive gas became a vital tool during the First World War, when access to helium was highly restricted, and this occurred again during the Second World War. Many of the potential uses of helium can be military in nature, including use as a non-reactive buffer for arc welding and as a lifting agent for balloons of all sizes. Helium is also used as a supercoolant in scientific experimentation and nuclear reactors.

Pure helium is not toxic, and exposure to the clear, odorless, and tasteless gas should not pose a health risk. However, excessive inhalation of helium can be dangerous, as the gas will act as an asphyxiate. In addition, helium inhaled directly from a pressurized tank may cause lung damage, and commercial helium such as that found in party balloons may be contaminated with other substances which are not healthy to inhale.