What is NH4 and NO2?

[Booswalia]

Is there a list somewhere that translates all of these symbols? It really is a struggle if you've never had any formal training in chemistry.

[Cearbhaill]

Handy Dandy Abbreviations Listing (http://www.megapathdsl.net/~fmariani/abbreviations.htm) :D

[RTR]

NH4 is the ammonium ion (NH3 is ammonia).

NO2 is the nitrite ion.

[Booswalia]

Thanks a bunch.