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 > >   name        Nathan
 > >   status      student
 > >   age         19

 > >   Question -  When looking at the periodic table Argon shows up as a rare
 > > or noble gas. A rare element is supposed to have been concentrated in the
 > > primordial or primary atmosphere of the earth that was largely lost
 > > during the early stages of the earth's history. However, Argon is the 4th
 > > most abundant constituent of the atomosphere. So my question is how can
 > > this be?

Argon hung around because argon atoms are massive (compared to oxygen,
for example) and therefore hard for the sun to blow away.  (It takes
more energy to raise an argon atom out of earth's gravity than to raise
an oxygen atom.)

However, argon is less abundant than many elements with smaller atomic
masses, and this is because it doesn't form compounds or molecules.
Lots of oxygen that might otherwise have been blown away was locked in
the form of silicon dioxide (sand), water, etc.

Tim Mooney 

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Funny definition of "rare element."  Argon is a noble gas.  It's fairly
abundant because it has a very stable nucleus.  It's also fairly heavy, so
it's not lost from the atmosphere as easily as helium or neon.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

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Hello,
You are correct about the abundance of Argon. I think they are called rare 
gases because when they were discovered, they were thought to be very 
rare.  I do not know who coined the term but we know that Argon was 
discovered by Lord Rayleigh and Sir William Ramsay after they realized that 
air with its oxygen removed was slightly heavier than pure nitrogen, and 
thus had additional components.   The abundance of Argon was later realized 
but the name remained.

The six elements collectively referred to as the rare, noble, or inert 
gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and 
radon (Rn).  In addition to be rare, these were thought to be inert or 
noble, that is, they would not react with other elements.   The word noble 
was used to draw parallel with the (British ?) nobles who did not mix with 
the commoners.  In the 1960s, however, it was found that some of these 
noble gases are not all that noble, and actually can form stable chemical 
compounds (e.g., reaction between xenon and fluorine.)   The Noble people, 
I think, had began mixing with the commoners long before that date!

AK
Dr. Ali Khounsary
Advanced Photon Source
Argonne National Laboratory
Argonne, IL 60439
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