Measurements of the spontaneous fission half-lives of nuclides of elements Z = 82 through 109 have been compiled (cutoff date of April 1998) and evaluated. Recommended values are tabulated along with total half-lives.

In this article, some of the people and events that helped shape my long career in chemistry are recalled. The status of women has changed dramatically over these years as have chemistry and my specialties of radiochemistry and nuclear chemistry. When I entered Iowa State College in 1944 as an Applied Art major, freshman chemistry was a required subject. It was my first course in chemistry and was taught by a woman chemistry professor. She emphasized chemistry as a basic science with opportunities in both fundamental and applied research and told of Marie Curie's discovery of radium as well as practical applications in everyday life. Because of her inspiring lectures, I soon decided to change my major to chemistry! Subsequent undergraduate research in nuclear chemistry exposed me to the thrill of discovering new isotopes. 1 earned my B.S. (1944), Ph.D. (1951) in Chemistry (nuclear) and married fellow graduate student Marvin Hoffman (1951). I quickly learned that "you can't do it all by yourself"! I had outstanding help at home and a husband who understood that I must continue my career even after we had two children. The opportunity to travel, attend international conferences, pursue sabbaticals abroad, accept lectureships in many different countries ranging from North and South America, to China, Japan and Europe helped broaden my horizons and understand the potential 'uniting power' of science in the solution of world problems.

The existing data on neutron-emission, kinetic-energy and mass distributions, and half-lives for spontaneous fission of the heavy actinides are reviewed. A comparison of the data for the Fm isotopes with heavier and lighter nuclides suggests that the properties of the heavy Fm isotopes may be unique and can qualitatively be explained on the basis of fragment shell effects, i.e., symmetric fission results in two fragments with configurations close to the doubly magic 132 Sn nucleus. The effect of excitation energy and the use of systematics and theoretical predictions of fission properties and half-lives in the identification of new heavy element isotopes is discussed.

A brief history of the development and some of the first uses of "atom-at-a-time" techniques to investigate the chemical and nuclear properties of the actinide and transactinide elements are presented. The currently known transactinides (all elements with Z > 103) were discovered using physical (nuclear) techniques rather than chemical separation techniques because of their short half-lives and low production rates and the difficulty in accurately predicting chemical properties of the heaviest elements because of relativistic effects. Some of the constraints on systems suitable for such studies and whether these tracer-scale results can be extended to the macro-scale are discussed. The relevance and importance of the methods and their potential for application to some current problems such as nuclear forensics and proliferation and environmental concerns are considered. The value of graduate research utilizing such techniques in helping to attract and educate the next generation of nuclear scientists is highlighted.

Abstract This year (2009) marks the 140th Anniversary of Mendeleev's original 1869 periodic table of the elements based on atomic weights. It also marks the 175th anniversary of his birth in Tolbosk, Siberia. The history of the development of periodic tables of the chemical elements is briefly reviewed beginning with the presentation by Dmitri Mendeleev and his associate Nikolai Menshutkin of their original 1869 table based on atomic weights. The value, as well as the sometimes negative effects, of periodic tables in guiding the discovery of new elements based on their predicted chemical properties is assessed. It is noteworthy that the element with Z=101 (mendelevium) was identified in 1955 using chemical techniques. The discoverers proposed the name mendelevium to honor the predictive power of the Mendeleev Periodic Table. Mendelevium still remains the heaviest element to have been identified first by chemical rather than nuclear or physical techniques. The question concerning whether there will be a future role for the current form of the periodic table in predicting chemical properties and aid in the identification of elements beyond those currently known is considered.

This year (2011) marks the 100th Anniversary of the award of the Nobel Prize in Chemistry to Marie Sklodowska-Curie for her discoveries of radium and polonium and her studies of their properties. The United Nations has proclaimed 2011 as the "International Year of Chemistry", partly in recognition of this 100th anniversary. A resolution of the Sejm of the Republic of Poland has also established 2011 as the Year of Maria Sklodowska-Curie. Marie Curie has been celebrated this year by a host of prestigious societies and in many countries all around the world for winning Nobel Prizes in both Physics (1903), for the discovery of radioactivity together with husband Pierre Curie and Henri Becquerel, and Chemistry (1911). She was the first woman to win Nobel Prizes in both Physics and Chemistry and the only one to date to win prizes in both physics and chemistry. Also remarkable was that after Pierre Curie's tragic and untimely death in 1906, she was put in charge of his lectures and laboratory, thus marking the first time in France that a woman occupied such a prestigious academic position, and opening the way for other women to follow. The current article will focus on some of the other notable accomplishments of Marie Curie that are not as commonly recognized, including her organizational and persuasive abilities, and her unique contributions as a teacher, mentor, research center founder, and laboratory "la Patronne".

This chapter gives a brief summary of the reported discoveries, confirmation, and nuclear properties of the claimed and confirmed transactinide elements through the year 2004. However, the primary emphasis is on the chemical properties – experimental, theoretical, and predicted – of the transactinides and a comparison of measured properties with theoretical predictions. The experimental studies of chemical properties are especially challenging because of the low production rates and the short half-lives and the need for very special facilities and the use of atom-at-a-time chemistry. The discovery of a new element must furnish evidence that its atomic number is different from those of all the currently known elements and first claims to discovery often lacked such positive identification. As a result, there were uncertainties and controversies over priority of discovery, nuclear and chemical properties, and assignment of names. The first positive identification of the atomic number of all these elements was accomplished using ‘physical’ rather than chemical techniques.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Periodic Table: Key to Past "Elemental" Discoveries—A New Role in the Future?Darleane C. Hoffman View Author Information Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720Cite this: J. Chem. Educ. 2009, 86, 10, 1122Publication Date (Web):October 1, 2009Publication History Received3 August 2009Published online1 October 2009Published inissue 1 October 2009https://pubs.acs.org/doi/10.1021/ed086p1122https://doi.org/10.1021/ed086p1122research-articleACS PublicationsRequest reuse permissionsArticle Views621Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Elements,Isotopes,Order,Toxicological synergy Get e-Alerts

Excitation functions for the 1n and 2n exit channels of the Pb-208(V-51, xn)(259-x)Db reaction were measured. A maximum cross section of the 1n exit channel of 2070(-760)(+1100) pb was measured at an excitation energy of 16.0 +/- 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660(-370)(+450) pb was measured at 22.0 +/- 1.8 MeV excitation energy. The 1n excitation function for the Bi-209(Ti-50, n)(258)Db reaction was remeasured, resulting in a cross section of 5480(-1370)(+1730) pb at an excitation energy of 16.0 +/- 1.6 MeV, in agreement with previous values [F. P. Hessberger et al., Eur. Phys. J. A 12, 57 (2001)]. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier.

Some of the techniques used in atom-at-a-time investigations of both nuclear and chemical properties of transactinide elements will be discussed. Constraints on the systems that are valid for exploring chemical properties when only a few atoms at a time are available and recent developments in instrumentation are considered. The current status of investigations of the chemical properties of the transactinides is summarized and prospects for additional studies are evaluated.