In this article, author has explained the discovery, abundance, properties and uses of helium element.
Helium is the second most abundant element in the universe. It is a colorless, tasteless, odorless, and monoatomic noble gas. It is present at the top of the noble gas group and is the least reactive of all the elements. It does not react with any element and ion therefore there are no helium-bearing minerals in nature. It was first observed after studying the sun. it was named after the Greek word “Helios” meaning sun.
Discovery of helium
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Helium was discovered by French astronomer Jules Janssen in 1868. In India, Janssen observed the solar eclipse through a prism. Janssen observed a bright yellow spectral line emerging from the chromospheres of the Sun. Joseph Norman also observes the same line from the sun through London smog. He considered it an element and named it helium.
Abundance of helium
Helium is the second most abundant element in the universe. The first one is hydrogen. It is found in all the stars. It is produced by the alpha-particle decay of radioactive elements on the Earth. Some helium also escapes into the atmosphere which contains about 5 parts per million volume. It is uneconomical to extract helium from the air. The major source of helium is natural gas which contains 7% helium.
Properties of helium
- Symbol: He
- Atomic Number: 2
- Atomic Weight: 4.00260
- Classification: A noble gas and a nonmetal
- Source: natural gas
- Appearance: colorless, odorless gas
- Reactivity: non-reactive
- Phase at Room Temperature: Gas
- Density: 0.0002 g/cm3
- Melting Point: -272.20°C, -457.96°F
- Boiling Point: -268.93°C, -452.07°F
- Heat of vaporization: 0.1KJ/mol.
- Thermal conductivity: 0.15 J/m sec k.
- Polarizability: 0.198Å3
- Discovered by: Pierre Janssen in 1868
- Isotopes: 3He, 4He
- 3He abundance: 0.000134%
- 4He abundance: 99.9999%
- 3He atomic mass: 3.016
- 4He atomic mass: 4.003
Position of helium in the periodic table
- Group: 18
- Period: 1
- Block: s
- Electronic configuration: 1s2
Uses of Helium
- Helium is used in the welding of metals (aluminum) as an inert gas atmosphere.
- Helium is used in rocket propulsion. This is because helium is still a gas at liquid-hydrogen temperature.
- It is a lifting gas in meteorology such as lifting balloons.
- Liquid helium is the coldest substance, therefore, use in cryogenics as a coolant.
- It is used for breathing at high pressure. Helium is mixed with oxygen and used in scuba diving.
- It is used in caisson work because of its low solubility in the bloodstream.
- It is used in the production of crystals like germanium crystals and silicon crystals.
- It is used to detect pipeline leakage detection because helium can diffuse through solids much faster than air.
- Helium is used in gas chromatography as a gas carrier.
- Liquid helium is used in magnetic resonance imaging due to its low melting point.
- It is also used in superconducting magnets.