Name       : Helium
Symbol     : He
Atomic #   : 2
Atom weight: 4.0026
Melting P. : < -272.2
Boiling P. : -268.934
Oxidation  : 0
Pronounced : HEE-li-em
From       : Greek helios, "sun"
Identified : Pierre Janssen and Joseph Norman Lockyer in 1868
Appearance : Inert, colorless, odorless, tasteless gas
Note       : Second to hydrogen in abundance in the cosmos
          
[Properties]

  Helium heads the list of Group 0 elements along the right-hand edge of 
the periodic chart - a group more commonly called the noble gases.  These
gases are most noted for their relative inactivity.
  Helium and the other noble gases were once considered totally inert;
that is, it was thought they could not react with any other element to
produce compounds.  There was good theoretical and practical evidence to
support this earlier view.  First, from a theoretical viewpoint, all
electrons orbits for the noble gases are completely filled.  This means
the atoms are extremely stable and neither give up nor gain electrons
under normal circumstances.  From a practical point of view, no one had
found a noble gas compound until 1962.
  Nowadays it is possible to prepare stable compounds of the three
heavier noble gases: krypton (Kr), xenon (Xe), and radon (Rn).  The
lighter noble gases - Helium (He), neon (Ne), and argon (Ar) - still
pose a problem with regard to making stable compounds.  Researchers,
however, have seen evidence of an unstable ion that combines one of the
lighter noble gaseswith an atom of hydrogen.  In the case of helium,
this ion is HeH+.  Helium is the only element that cannot be converted
to a solid by lowering its temperature.  At ordinary atmospheric pressure,
helium is believed to remain a liquid at absolute zero.  Helium gas is
also noted for having an unusually high rate of expansion with heating.
And, although Helium is almost twice as dense as hydrogen, it has nearly
98% of hydrogen'slifting power.  This lifting power, combined with the
fact that it is non-flammable, makeshelium the preferred gas for
dirigibles, or blimps, as well as for toy balloons.