|WikiProject Chemistry||(Rated Stub-class, High-importance)|
Can one species be a subset of another, if you change the time scale?
For example, can O_2 (with any electronic state) be considered a single species that breaks into more specific species if you shorten the time scale (singlet versus triplet)?
Or more simply, is an element a species, which then breaks into subspecies according to ionization?
Listing a number of such examples would be helpful in understanding that "species" is a more subtle and general concept than just atom, molecule, ion, or radical. 188.8.131.52 (talk) 00:37, 17 January 2015 (UTC)