Spectrum Tubes, offered for sale by Sargent Welch.

 

http://sargentwelch.com/product.asp?pn=WLS68755-30W_EA

 

They offer every (collectable!) gaseous element, except fluorine.

Fluorine in glass tubes (not spectral tubes though), se above.

Difficult question.

 

Should 90 Th (the isotope Th 232), and 92 U (the isotope U 238) be regarded as collectable elements?

 

If making such an exception for 83 Bi, why not for these 2 actinide elements?

 

The difference is that the instability of Bi is a rather new knowledge, because of its very long half life (difficult measurement).

But it has been known since discovery of radioactivity that these 2 metals are radioactive.

 

The difference then is quantitative, not qualitative.