Helium topic

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Helium (He) is a colorless, odorless, tasteless, non-toxic, inert monatomic chemical element that heads the noble gas group in the periodic table and whose atomic number is 2. 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 light was first observed from a solar eclipse in 1868 by French astronomer Pierre Janssen who is jointly credited with the discovery of the element with... full article at wikipedia

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Chemistry

Chemical Element

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CAS ID

7440-59-7

Symbol

Edit	Atomic number

Edit	Atomic mass (g/mol)

4.0026

Edit	Electrons per shell

Edit	Electronegativity (Pauling scale)

21.0

Edit	Atomic radius

31.0pm

Edit	Covalent radius

32.0pm

Edit	Van der Waals radius

140.0pm

Isotopes

Edit	Melting Point

-272.2°C

Edit	Boiling Point

-268.93°C

Chemical series

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The original description for this topic was automatically generated from the Wikipedia article "Helium" licensed under the GNU Free Documentation License .