Properties of Group Five and Group Seven transactinium elements

Abstract

The detection and positive identification of the short-lived, low cross section isotopes used in the chemical studies of the heaviest elements are usually accomplished by measuring their α-decay, thus the nuclear properties of the heaviest elements must be examined simultaneously with their chemical properties. The isotopes 224 Pa and 266,267 Bh have been studied extensively as an integral part of the investigation of the heaviest members of the groups five and seven of the periodic table.The half-life of 224 Pa was determined to be 855±19 ms by measuring its α-decay using our rotating wheel, solid state detector system at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Protactinium was produced by bombardment of a bismuth target. New neutron rich isotopes, MeV.The chemical behavior of hahnium, Ha (element 105) was investigated using the fast on-line continuous liquid extraction and detection system SISAK-LISSY.Hahnium was not observed in this experiment following transport and extraction.Protactinium was used as on-line test of the apparatus to determine the experimental efficiency of the entire system. Unfortunately, the amount of protactinium observed after the extraction, compared to the amount produced, was extremely small, only 2.5%. The extraction of the protactinium test isotope indicated the efficiency of the apparatus was too low to observe the extraction of hahnium.The chemical behavior of oxychloride compounds of bohrium was investigated by isothermal gas adsorption chromatography in a quartz column at 180, 150, and 75°C. It was found to be less volatile than the corresponding compounds of the lighter group seven homologues, rhenium and technetium, which had been measured previously with the same apparatus. Assuming the bohrium compound to be BhO 3 Cl, the evaluated standard adsorption enthalpy, ∆H ads , of BhO 3 Cl on the quartz surface was calculated from Monte Carlo fits to the volatility data to be DedicationThis thesis is dedicated to the Reed Reactor Facility (RRF) of Reed College, Portland, Oregon and the Summer School in Nuclear Chemistry that was sponsored by the Division of Nuclear Chemistry and Technology of the American Chemical Society. These two institutions have maintained a commitment to undergraduate education in the field of nuclear chemistry that is unparalleled. It is my hope that Reed will soon replace the long missing radiochemistry professor of the chemistry department to echo this commitment to nuclear and radiochemistry. Without the education and the experience I received from the RRF and the contacts I made at the ACS summer school, I certainly would not be writing this thesis. No changes were made to the structure of the Periodic Table until 1944, when Glenn T. Seaborg postulated the existence of the actinide series, analogous to the lanthanide series (see Figure 1.1) [Seaborg 1945]. This seemingly simple extrapolation was not obvious given the data at the time, and led to the nearly immediate discovery of americium and curium. Before Seaborg's fo...