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Helium Properties

Helium

Description

 

Helium is a 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. It is the second most abundant element in the universe. It is used in cryogenics, particularly the cooling of superconducting magnets, with the main commercial application in MRI scanners. Helium's other industrial uses as a pressurizing and purge gas, and a protective atmosphere for arc welding and processes such as growing crystals to make silicon wafers, account for half of its use. Economically minor uses, such as lifting gas in balloons and airships are popularly known. As with any gas with differing density from air, inhaling a small volume of helium temporarily changes the timbre and quality of the human voice. In scientific research, the behavior of two fluid phases of helium-4, helium I and helium II, is important to researchers studying quantum mechanics and to those looking at the effects that temperatures near absolute zero have on matter.

Chemical Properties

Appearance Colorless Gas
Atomic Number 2
Atomic Weight 4.0026 g/mol
Block s
Boiling Point −268.9 °C
CAS Number 7440-59-7
Class 2.2
Crystal Structure Hexagonal Close-Packed
Density 0.1786 g/l
EINECS Number 231-168-5
Electron Configuration 1s2
Group 18
Ionization Energy 2372.3 kJ/mol
Melting Point −272.2 °C
PG NA
Period 1
RTECS Number MH6520000
Symbol He