Figure 1:
Three-dimensional representation of the theoretical island of stability in nuclear physics. The half-life of nuclides is plotted as a function of proton (Z) and neutron (N) number. The continent of stable elements ends at the lead–bismuth cape, and a region of relative stability appears around the isotopes of thorium and uranium (Z=90,92). In the region of the heaviest (superheavy) elements, theory predicts an “island of stability” around proton number 114 or 120 and neutron number 184.