posted by penelope .
the longest lived radioactive isotope yet discovered is the beta-emitter tellurium-130.it has been determinded that it would take 2.4 x 10^21 years for 99.9% of this isotope to decay. write the equation for this reaction, and identify the isotope into which tellurium-130 decays.
52130Te ==> -1oe + X
The subscripts must add up and the superscripts must add up. I have shown the beta particle (an electron) with -1 charge and 0 mass. When you know the atomic number, place it at the lower left hand of X as a subscript and the mass number will be a superscript at the top left. Then look on the periodic table and identify the element X. It's tough to write these subscripts and superscripts so if I've goofed on one of them I will redo it.
It look ok to me.