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Essay Archive - Helium
Helium
Helium, symbol He, inert, colorless, odorless gaseous element. In
group 18 (or VIIIa) of the periodic table, helium is one of the noble gases.
The atomic number of helium is 2. The French astronomer Pierre Janssen
discovered helium in the spectrum of the corona of the sun during an
eclipse in 1868.
Helium is the lightest of all gases except hydrogen. Helium
solidifies at -272.2° C (-457.9° F) at pressures above 19,000 torr (25
atmospheres); helium boils at -268.9° C (-452.0° F) and has a density of
0.1664 g/liter at 20° C (68° F). The atomic weight of helium is 4.003.
Helium, like the o....
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