Element helium

Helium is a noble gas and, after hydrogen, the most abundant element in the universe. The chemical symbol for helium is HE.

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1. Element helium

Helium is a chemical element with an atomic number of 2. It belongs to the group of noble gases. After hydrogen, helium is the most abundant element in the universe.

The helium nucleus is made of two protons and two neutrons, and two electrons orbit in its atomic orbits. The chemical symbol for helium is HE.

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2. Hel. Discovery of an element

The element helium was discovered in 1868. The discovery was made by the English astronomer Norman Lockyer and the English chemist Edward Frankland.

Scientists, observing the solar eclipse in the spectrum of the chromosphere, observed an orange fringe emitting at a wavelength of 587.6 nm.

Lockyer and Frankland could not assign a color to any of the previously known elements, so they named it helium, after the Greek sun god Helios.

For the next 27 years, helium was considered absent on Earth. It was not until 1895 that the Scottish chemist William Ramsay isolated helium from uranium ore.

3. Helium occurrence

Helium is very common in the universe. It is the most abundant element after hydrogen.

However, on Earth, helium is present in trace amounts because it does not form compounds with other elements and because it is a very light gas. Helium rises to the upper atmosphere as it "escapes" from Earth.

The concentration of helium in the earth's crust is 8 parts per billion. Helium is present in uranium, thorium and carnotite ores.

However, the greatest natural source of helium on Earth is natural gas. For the needs of industry, helium is obtained from natural gas deposits.

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4. Hel. Physical and chemical properties

Helium is a gas that is 7 times lighter than air. Helium has no smell or taste. Of all the known elements, helium has the lowest melting and boiling points. Helium dissolves very poorly in water.

This gas does not form any permanent chemical compounds and is the second, after Neon, the least reactive of all elements.

5. Helium isotopes

There are three known helium isotopes: 3He, 4He, 6He. In nature there are - H3 and H4. The relative composition of these isotopes is not constant and depends on the source of origin.

The H6 isotope is obtained in laboratory conditions. However, it is very fragile.

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6. The use of helium

Diving cylinders are filled with a helium-oxygen mixture because this gas, unlike nitrogen, has a very low solubility in the blood. It is therefore less likely to develop decompression sickness.

In medicine, mixtures of oxygen, nitrous oxide and helium are used. Helium is also filled in gas thermometers and fluorescent lamps.

Helium is used as a protective gas for welding in an oxygen-free atmosphere. In liquid form, helium is used to cool superconductors.

Unlike hydrogen, helium is non-flammable. That is why it is used to fill weather, advertising and toy balloons.

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