Ask A Scientist Chemistry Archive

From:       laurens
Text:       Is hydrogen a metallic element?  If not, why is it on the left 
side of the periodic table?

Response #:  1 of 2
Author:      woodford
Text:        Hydrogen is not a metallic element despite the placement on the 
left side of the periodic chart.  I think that most modern periodic tables 
place it both on the upper left (its periodic position) and on the upper right 
next to Helium (its position as a gas).  The reason that it was put on the 
upper left of the table originally is because the column IA is home to all 
elements with 1 electron in the outermost s-orbital.  Hydrogen certainly meets 
this criteria, however it is physical properties are more consistent with the 
gases grouped at the upper right.

Response #:  1 of 2
Author:      Robert Topper
Text:        Just to expand on Mike's answer a little.  The most common phase 
of hydrogen (that is, pure hydrogen) is hydrogen gas.  Two hydrogens form a 
chemical bond to form H2. H2 does have a lot of physical properties which are 
similar to the upper-right gases.  However, solid hydrogen can be formed at 
cryogenic temperatures (REAL cold) and there is some limited evidence that it 
may be metallic (i.e. conduct electrons like a metal does).  There are some 
decent theoretical reasons for this to happen too...but it is still an issue 
of some dispute if I recall.