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 beryllium-111111 is 141414 seconds. a sample of beryllium-111111 was first measured to have 800800800 atoms. after ttt seconds, there were only 505050 atoms of this isotope remaining. write an equation in terms of ttt that models the situation.