Every chemical element goes through natural exponential decay, which means that over time its atoms fall apart. the speed of each element's decay is described by its half-life, which is the amount of time it takes for the number of radioactive atoms of this element to be reduced by half. the half-life of the isotope dubnium-263263263 is 292929 seconds. a sample of dubnium-263263263 was first measured to have 102410241024 atoms. after ttt seconds, there were only 323232 atoms of this isotope remaining.