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A deep reservoir of primordial helium in the Earth

Noble gases, including helium, neon, and argon, are characterized by high chemical inertness which causes low reactivity with other materials and high volatility. Among them, 3He, 20Ne, and 36Ar are particular isotopes which ...

Bats found to have innate sense of speed of sound

A pair of researchers with Tel Aviv University's School of Zoology has found that bats have an innate sense of the speed of sound. In their paper published in Proceedings of the National Academy of Sciences, Eran Amichai ...

Researchers find bubbles speed up energy transfer

Energy flows through a system of atoms or molecules by a series of processes such as transfers, emissions, or decay. You can visualize some of these details like passing a ball (the energy) to someone else (another particle), ...

An improved safety standard for bionic devices

Applied physicists at the University of Sydney have proposed new standards to measure moisture leaks into bionic devices such as pacemakers, cochlear hearing implants and retinal replacements.

Size of helium nucleus measured more precisely than ever before

In experiments at the Paul Scherrer Institute PSI, an international research collaboration has measured the radius of the atomic nucleus of helium five times more precisely than ever before. With the aid of the new value, ...

Quantum wave in helium dimer filmed for the first time

Anyone entering the world of quantum physics must prepare themself for quite a few things unknown in the everyday world: Noble gases form compounds, atoms behave like particles and waves at the same time and events that in ...

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Helium

Helium (pronounced /ˈhiːliəm/) is the chemical element with atomic number 2, and is represented by the symbol He. 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 the elements and it exists only as a gas except in extreme conditions.

An unknown yellow spectral line signature in sunlight was first observed from a solar eclipse in 1868 by French astronomer Pierre Janssen. Janssen is jointly credited with the discovery of the element with Norman Lockyer, who observed the same eclipse and was the first to propose that the line was due to a new element which he named helium. In 1903, large reserves of helium were found in the natural gas fields of the United States, which is by far the largest supplier of the gas. Helium is used in cryogenics, in deep-sea breathing systems, to cool superconducting magnets, in helium dating, for inflating balloons, for providing lift in airships and as a protective gas for many industrial uses (such as arc welding and growing silicon wafers). Inhaling a small volume of the gas temporarily changes the timbre and quality of the human voice. The behavior of liquid helium-4's two fluid phases, helium I and helium II, is important to researchers studying quantum mechanics (in particular the phenomenon of superfluidity) and to those looking at the effects that temperatures near absolute zero have on matter (such as superconductivity).

Helium is the second lightest element and is the second most abundant in the observable universe, being present in in the universe in masses more than 12 times those of all the other elements heavier than helium combined. Helium's abundance is also similar to this in our own Sun and Jupiter. This high abundance is due to the very high binding energy (per nucleon) of helium-4 with respect to the next three elements after helium (lithium, beryllium, and boron). This helium-4 binding energy also accounts for its commonality as a product in both nuclear fusion and radioactive decay. Most helium in the universe is helium-4, and was formed during the Big Bang. Some new helium is being created presently as a result of the nuclear fusion of hydrogen, in all but the very heaviest stars, which fuse helium into heavier elements at the extreme ends of their lives.

On Earth, the lightness of helium has caused its evaporation from the gas and dust cloud from which the planet condensed, and it is thus relatively rare. What helium is present today has been mostly created by the natural radioactive decay of heavy radioactive elements (thorium and uranium), as the alpha particles that are emitted by such decays consist of helium-4 nuclei. This radiogenic helium is trapped with natural gas in concentrations up to seven percent by volume, from which it is extracted commercially by a low-temperature separation process called fractional distillation.

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