Helium is a chemical element that 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 this gas, 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. Its extreme stability 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 the element in concentrations ranging from 2 to 7%.
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 the gas 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 the gas can be dangerous, as it will act as an asphyxiate.
In addition, when inhaled directly from a pressurized tank, it may
cause lung damage, and commercial helium such as that found in party
balloons may be contaminated with other substances that are not healthy
to inhale.
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