June 10, 2012, 9:59 pm
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Vial of glowing ultrapure helium. Original size in cm: 1 x 5. Source: images-of-elements.com

Helium is a very small and extremely light gaseous element. It is odorless and tasteless. It is the least reactive of all elements: that is, it is inert and is not known to react with any other element or ion. As a result, there are no helium-bearing minerals. However, helium is given off as a by-product of the breakdown of radioactive elements in rocks and minerals.

A liquid helium bath, capable of chilling down to -269 degrees Celsius. (Source: The Boston University School of Medicine)

Helium was not first discovered on Earth; it was first discovered in the Sun! In 1868, the chromosphere of the Sun was studied during a solar eclipse. The study was done using an instrument that breaks a light into its spectrum, like a prism breaks sunlight into its rainbow colors. The instrument used is called a spectrometer. The French astronomer Janssen studied the spectrum produced during this event, and concluded that a new, yellow stripe was due to an element not previously known. In 1895, Sir William Ramsay proved the existence of helium on Earth in his studies of a radioactive ore material from Norway (the discovery of radium in 1898 showed that helium was indeed a by-product of the natural breakdown of radioactive elements). Helium was discovered to be an element by Norman Lockyer and Edward Frankland of England.

Studies of the molecules in the Earth’s atmosphere show that helium makes up .0004% of the atmosphere. In other words, there is one helium molecule for every 200,000 air constituents molecules (which includes oxygen, hydrogen, nitrogen, helium, etc.).

There is no helium in the human body, and since it is so inert, helium is not harmful to any life form.

Helium can be cooled enough to liquefy it; however, it is the only element that cannot be frozen solid at very low temperatures.


Previous Element: Hydrogen

Next Element: Lithium


Physical Properties
Color colorless
Phase at Room Temp. gas
Density (g/cm3) 0.0002
Hardness (Mohs) ---
Melting Point (K) ---
Boiling Point (K) 4.2
Heat of Fusion (kJ/mol) ---
Heat of Vaporization (kJ/mol) 0.1
Heat of Atomization (kJ/mol) 0
Thermal Conductivity (J/m sec K) 0.15
Electrical Conductivity (1/mohm cm) ---
Source natural gas
Atomic Properties
Electron Configuration 1s2
Number of Isotopes 7 (2 liquid)
Electron Affinity (kJ/mol) 0
First Ionization Energy (kJ/mol) 2372.3
Second Ionization Energy (kJ/mol) 5250.3
Third Ionization Energy (kJ/mol) ---
Electronegativity ---
Polarizability (Å3) 0.198
Atomic Weight 4.003
Atomic Volume (cm3/mol) 27.2
Ionic Radius2- (pm) ---
Ionic Radius1- (pm) ---
Atomic Radius (pm) 31
Ionic Radius1+ (pm) ---
Ionic Radius2+ (pm) ---
Ionic Radius3+ (pm) ---
Common Oxidation Numbers ---
Other Oxid. Numbers ---
In Earth's Crust (mg/kg) 8x10-3
In Earth's Ocean (mg/L) 7×10-6
In Human Body (%) 0%
Regulatory / Health
CAS Number 7440-59-7
OSHA Permissible Exposure Limit (PEL) No limits
OSHA PEL Vacated 1989 No limits
NIOSH Recommended Exposure Limit (REL) No limits
Mineral Information Institute
Jefferson Accelerator Laboratory
Since helium was first discovered by studying the Sun, its name was derived from the Greek word for sun, helios.


Some natural gas deposits have as much as 7% helium. Such deposits have been found in Texas, Russia, Poland, Algeria, China and Canada. Helium extracted from these natural gas reserves is the single source of helium.

It is believed the world helium resources – excluding those of the United States – totals 15.1 billion cubic meters. It is estimated that the United States has helium resources of 11.1 billion cubic meters.


Because it is inert, liquefied helium has a number of applications. It is used in cryogenics to freeze biological materials for long-term storage and later use (24%). It is also used in welding and to create controlled atmospheres. It is used to detect leaks in pipes. Its inert nature makes helium useful for cooling nuclear power plants.

Since helium molecules are so small, mixtures of helium and oxygen have proven to be useful in treating people with severe asthma or lung problems. It is also mixed with oxygen for use in deep-sea diving.

Most people are certainly familiar with the use of helium as a lighter-than-air substance. It holds up our birthday balloons. The motorized blimps that hover over sports stadiums are held up by helium. They are, in reality, very large balloons.

Substitutes and Alternative Sources

For super cold applications (particularly, at temperatures below –429 degrees Fahrenheit there is no adequate substitute for helium. Another inert gas, argon, can be used in place of helium for some welding applications. Hydrogen can also be used in place of helium, but only in situations where the explosive nature of hydrogen will not be a problem. Hydrogen might be a good substitute for helium in some deep-sea diving situations.

Further Reading


Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Mineral Information Institute. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Mineral Information Institute should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.




Institute, M. (2012). Helium. Retrieved from http://www.eoearth.org/view/article/153470


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