All the isotopes of elements beyond lead are radioactive. Some have lifetimes of tens of millions of years, while others are fractions of a second. Nuclear physicists and chemists know that isotopes that have magic numbers of neutrons or protons are more stable than others. They have proposed that very heavy isotopes with a neutron number around 180 and a proton number around 110 should be more stable than those with fewer or greater neutrons and protons. A glance at the table of elements beyond uranium shows that elements around 110 have longer lifetimes than others. But researchers have not yet been able to create isotopes with enough neutrons to reach this island.