Raymond Cruz's Tuco Salamanca would have been retained for the entire run of season 2 if Cruz hadn't landed a major role on the TV series The Closer (2005).
That man pays my salary!
In the opening credits, the "Br" and "Ba" in "Breaking Bad" are presented as if they are entries from a periodic table of elements. The additional pieces of information included are atomic number, atomic mass, oxidation states, and electron shell configuration. Each of these is depicted accurately for both Br (bromine) and Ba (barium), except the electron shell configuration for Ba is copied verbatim from Br. The periodic table that the entry for Ba is visually extracted from contains the correct information. The creators were most likely aware of this, but thought the opening had enough merit to warrant this disregard for correctness under artistic license.
Opening credits use chemical symbols from the periodic table of elements as part of names : bromine (Br), and barium (Ba) for the title, none for creator Vince Gilligan (except when he gets a V for Vanadium), one for cast and crew members.
All episodes were rerun on an on-demand cable channel in some areas, without commercials but with additional scenes not included on AMC.