TIL that Helium (He) is the only element on the periodic table that was not discovered on Earth. It was found when analyzing the sun’s spectrum, hence its name which comes from the Greek god of the sun Helios.

Authored by education.jlab.org and submitted by Plank601

2 He Helium 4.002602 Atomic Number: 2 Atomic Weight: 4.002602 Melting Point: 0.95 K (-272.2°C or -458.0°F) Boiling Point: 4.22 K (-268.93°C or -452.07°F) Density: 0.0001785 grams per cubic centimeter Phase at Room Temperature: Gas Element Classification: Non-metal Period Number: 1 Group Number: 18 Group Name: Noble Gas

What's in a name? For the Greek god of the sun, Helios.

Say what? Helium is pronounced as HEE-lee-em.

Helium, the second most abundant element in the universe, was discovered on the sun before it was found on the earth. Pierre-Jules-César Janssen, a French astronomer, noticed a yellow line in the sun's spectrum while studying a total solar eclipse in 1868. Sir Norman Lockyer, an English astronomer, realized that this line, with a wavelength of 587.49 nanometers, could not be produced by any element known at the time. It was hypothesized that a new element on the sun was responsible for this mysterious yellow emission. This unknown element was named helium by Lockyer.

The hunt to find helium on earth ended in 1895. Sir William Ramsay, a Scottish chemist, conducted an experiment with a mineral containing uranium called clevite. He exposed the clevite to mineral acids and collected the gases that were produced. He then sent a sample of these gases to two scientists, Lockyer and Sir William Crookes, who were able to identify the helium within it. Two Swedish chemists, Nils Langlet and Per Theodor Cleve, independently found helium in clevite at about the same time as Ramsay.

Helium makes up about 0.0005% of the earth's atmosphere. This trace amount of helium is not gravitationally bound to the earth and is constantly lost to space. The earth's atmospheric helium is replaced by the decay of radioactive elements in the earth's crust. Alpha decay, one type of radioactive decay, produces particles called alpha particles. An alpha particle can become a helium atom once it captures two electrons from its surroundings. This newly formed helium can eventually work its way to the atmosphere through cracks in the crust.

Helium is commercially recovered from natural gas deposits, mostly from Texas, Oklahoma and Kansas. Helium gas is used to inflate blimps, scientific balloons and party balloons. It is used as an inert shield for arc welding, to pressurize the fuel tanks of liquid fueled rockets and in supersonic windtunnels. Helium is combined with oxygen to create a nitrogen free atmosphere for deep sea divers so that they will not suffer from a condition known as nitrogen narcosis. Liquid helium is an important cryogenic material and is used to study superconductivity and to create superconductive magnets. The Department of Energy's Jefferson Lab uses large amounts of liquid helium to operate its superconductive electron accelerator.

Helium is an inert gas and does not easily combine with other elements. There are no known compounds that contain helium, although attempts are being made to produce helium diflouride (HeF 2 ).

Estimated Crustal Abundance: 8×10-3 milligrams per kilogram

Estimated Oceanic Abundance: 7×10-6 milligrams per liter

Number of Stable Isotopes: 2 (View all isotope data)

TheEnKrypt on December 5th, 2019 at 14:26 UTC »

For those interested, there is the Periodic table showing the cosmological origin of each element

All the elements that come together to form you, were forged in exploding star(s) and the Big Bang.

Synaptic_Impulse on December 5th, 2019 at 14:25 UTC »

Interestingly, there's another element that was well on it's way to only being discovered in stars in the same way as helium, namely:

Technetium (Element #43).

Supposedly there is such little naturally occurring Technetium on Earth, that the chances of finding it are effectively near zero.

It would take some seriously sophisticated lab analysis to find it, that wasn't possible in the 1800's and early 1900's. Even today's labs would have a tough time finding it. (The best chance to find it is within uranium samples.)

Which is odd...

Given that it's element #43, and not one of those strange high numbered exotic "artificial" elements, and it's right there in the middle of the shiny-silvery-metal groups on the periodic table...

You would think it would be possible to find some naturally occurring lumps of it on Earth, but no. It just isn't there in any observable form of metal/rock lumps.

NEXT... given that it has a close to zero presence rate on Earth, you would then be inclined to think that it would have been most likely first discovered/observed existing only in stars, the same way helium was.

But no, you would be wrong again!

Essentially, it was first discovered/observed in the early era of cyclotrons (particle accelerators), when a reflective sheet of foil was analyzed after many particle collisions.

There on the foil, were the first observed atoms of Technetium, created artificially by smashing particles together.

So ya, otherwise, if no one had ever observed it in the residue of particle accelerators, then the only other place we would have been able to view/observe it would be in stars themselves (the same way helium was first observed).

unnaturalorder on December 5th, 2019 at 13:55 UTC »

Helium, the second most abundant element in the universe, was discovered on the sun before it was found on the earth. Pierre-Jules-César Janssen, a French astronomer, noticed a yellow line in the sun's spectrum while studying a total solar eclipse in 1868. Sir Norman Lockyer, an English astronomer, realized that this line, with a wavelength of 587.49 nanometers, could not be produced by any element known at the time. It was hypothesized that a new element on the sun was responsible for this mysterious yellow emission. This unknown element was named helium by Lockyer.

The hunt to find helium on earth ended in 1895. Sir William Ramsay, a Scottish chemist, conducted an experiment with a mineral containing uranium called clevite. He exposed the clevite to mineral acids and collected the gases that were produced. He then sent a sample of these gases to two scientists, Lockyer and Sir William Crookes, who were able to identify the helium within it. Two Swedish chemists, Nils Langlet and Per Theodor Cleve, independently found helium in clevite at about the same time as Ramsay.

If I recall my Percy Jackson expertise, he was then overthrown by Apollo.