Helium Isotopes

Helium Safety Data Sheet (SDS) in gas form - Download pdf file
Download Helium SDS in gas form

Properties of Helium Isotopes:

Helium Information

Helium is a colourless, odourless gaseous nonmetallic element. It belongs to group 18 of the periodic table. This element has the lowest boiling point of all elements and can only be solidified under pressure. Within the eighteenth group, helium is on the second place in the earth's crust (after argon). Helium is chemically inert, no known compounds. It was discovered in the solar spectrum in 1868 by Lockyer. Helium has 9 isotopes. 3 of them are naturally occurring, 2 of which are stable ones. It is interesting to know the ending "um" (Helium) characteristic of metals was used in the element name as Lockier assumed that the element he discovered was a metal. By analogy with other noble gases, it would be logical to give him the name "Helion". In modern science, the name "helion" is attached to the nucleus of the light helium isotope helium-3. Helium is named after the Greek Titan of the Sun, Helios.Most of the earth's helium present today is created by the natural radioactive decay of heavy radioactive elements (thorium and uranium although there are other examples), since the alpha particles emitted by such decays are composed of helium-4 nuclei.Helium is present in about 24% of the total mass of elements, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to that in both the Sun and Jupiter. Earlier terrestrial helium was considered a non-renewable resource, because once in the atmosphere it easily disappears into space. However recent studies show that helium formed deep in the bowels of the earth as a result of radioactive decay can accumulate in reserves of natural gas in a larger than expected amount, in some cases released as a result of volcanic activity.If electric current is passed through a tube filled with helium, discharges of various colors can be observed. The colors depend mainly on the gas pressure in the tube. Typically the visible light in the helium spectrum is yellow. If the pressure is reduced the color changes to pink, orange, yellow, bright yellow, yellow-green and green. The reason is in the presence of several series of lines in the helium spectrum located in the range between the infrared and ultraviolet parts of the spectrum.

Helium is used in balloons, deep sea diving and welding. It is also used in very low temperature research. Helium is a convenient indicator for geologists. The location of deep faults can be determined on the surface of the Earth using helium imaging. Helium as a decay product of radioactive elements saturating the upper layer of the earth's crust seeps through cracks and rises into the atmosphere. Near such cracks, and especially at their intersections, the concentration of helium is higher. This phenomenon was first established by the Soviet geophysicist I.N. Yanitsky during a search for uranium ores. This pattern is used to study the deep structure of the Earth and to search for ores of non-ferrous and rare metals.Leak detection is one of the industrial applications of helium. Since helium diffuses through solids three times faster than air, it is used as an indicator gas for detecting leaks in high-vacuum equipment (such as cryogenic tanks) and high-pressure containers. The object that is being tested is placed in a chamber. The chamber is then evacuated and filled with helium. Helium that escapes through leaks is detected by a sensitive device (helium mass spectrometer). The measurement procedure is called integrated helium testing and is usually automatic.Helium mixtures, such as trimix, heliox and heliair, are used for deep immersion, since helium does not have narcotic properties as a breathing gas. Such mixtures reduce the effect of narcosis which intensifies with increasing depth. Respiratory gas density increases as pressure increases with depth. It is found that low molecular weight helium significantly reduces the effort of breathing by reducing the density of the mixture.When mixed with a heavier gas such as xenon, helium is useful for thermoacoustic cooling due to its low Prandtl number and high heat capacity coefficient. Helium inertness has environmental benefits over conventional refrigeration systems, which contribute to global warming or depletion of the ozone layer.

back to list of enriched isotopes in alphabetical order