  Using the Planck scale as an absolute bound of half-life, we give a quick
estimate, in the manner of Feynman's fine-structure method, of the highest
possible atomic number. We find, upon simple extrapolation, that element 168
would constitute the end of the Periodic Table and its isotope with atomic
weight 411, being the most stable. These are remarkably close to current best
estimates obtained from sophisticated and much more involved Hartree-Fock
calculations.
