He

Overview

He is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.

Properties

Physical Properties

Helium is the second lightest and second most abundant element in the observable universe, being present in about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and Jupiter.

Chemical Properties

Helium is chemically inert and does not form compounds under normal conditions. It is used in applications where a non-reactive atmosphere is needed, such as in arc welding and in growing silicon and germanium crystals.

Uses

Helium has several important applications due to its unique properties:

• Cryogenics: Helium is used as a coolant for superconducting magnets in MRI scanners and other cryogenic applications.
• Breathing Mixtures: Helium is used in breathing gas mixtures for deep-sea diving to prevent nitrogen narcosis.
• Balloon Inflation: Due to its low density, helium is used to fill balloons and airships.
• Leak Detection: Helium is used as a tracer gas for detecting leaks due to its small atomic size.

Biological Role

Helium is not known to have any biological role. It is non-toxic and is not absorbed by the body. However, inhaling helium can displace oxygen in the lungs and lead to asphyxiation if done in a confined space.

Safety

While helium is non-toxic and inert, it can pose a suffocation hazard if it displaces oxygen in a confined space. It is important to ensure adequate ventilation when using helium in large quantities.

Production

Helium is extracted from natural gas through a process of fractional distillation. The largest reserves of helium are found in the United States, particularly in the Hugoton and Panhandle fields.

History

Helium was first detected in the solar spectrum by Jules Janssen and Norman Lockyer in 1868. It was named after the Greek god of the sun, Helios. It was later isolated on Earth by William Ramsay in 1895.

See Also

• Noble gas
• Periodic table
• Cryogenics