1. Lesson 14 The Transuranium Elements

2. The Basics 117 known elements, 1-118, no 117 All elements beyond 92 man-made

5. Chemistry of the heaviest elements

8. Theoretical Predictions

9. Methods of Heavy Element Synthesis Cold fusion Pb, Bi as target Massive Projectile E*~ 13 MeV, high survival Big fusion hindrance Used to synthesize 107- 113

10. Methods of Heavy Element Synthesis Hot fusion Reaction of lighter projectile with actinide target Low fusion hindrance High E* (30-50 MeV), low survival Used to synthesize 102- 106, 113-118

11. σ EVR = “stick” x “diffuse” x “survive” σ EVR = σ CN W sur σ CN = ∑σ capture (E cm,J)P CN (E cm,J) Capture cross sections σ capture ↔ Critical reviews of existing data by Swiatecki, Wilczynska and Wilczynski (PRC 74, 044607 (2006) Zagrebaev, PRC 64, 034606;65, 014607 Understanding heavy element synthesis

12. W sur evaluated from Vandenbosch and Huizenga expression B n, B f from Möller et al., (ADNDT 39,213; 59, 185) Excitation Energy Dependence of B f from Ignatyuk (Yad. Fiz. 21, 185)

13. How well can we describe observations?

15. How do we measure the production of new elements and nuclei?

16. History of Heavy Element Discoveries G.T. Seaborg and W. Loveland, The Elements Beyond Uranium S. Hofmann, On Beyond Uranium The textbook

17. Superheavy elements The allegorical picture has stuck even though it is wrong. There is no “island of stability” “superheavy” = “shell-stabilized”

18. Current view

21. Chemistry of the Heaviest Elements Relativistic Effects important since electron velocities approach that of the speed of light. Must use Dirac equation rather than the Schrodinger equation. Already known in Au, etc.

22. Relativistic Effects in Atomic Physics and Chemistry In high Z atoms. speed of inner electrons approaches c, mass of electron increases. Radius of orbits contracts. For Sg,  =0.77, a/a 0 =0.64 This defines the “direct relativistic effect”, ie. contraction of s and p 1/2 orbitals

23. Direct Relativistic Effect

24. “Indirect” Relativistic Effect Due to contraction of s and p 1/2 orbitals, outer electrons are more effectively screened and outer p,d,f orbitals expand.

25. Spin-Orbit Splitting Levels with > 0, are split into and

26. Effect of This

27. The “new” Aufbau diagram

28. Au--and heavier elements Contraction of 6s, expansion of 5p orbitals reduces the energy difference between these orbitals to that of a photon of blue light-> Au absorbs blue light and appears yellow. Non-relativistic -> Au would be unable to absorb light

30. Chemistry Apparatus Rapid chemistry Both gas and liquid systems Chemistry separate from production.

31. Chemistry Apparatus

32. Chemistry of Element 112

33. Chemistry of element 114 3 events observed at Dubna by PSI group, corresponding to 287 114, 288 114, and 289 114 from 48 Ca + 242,244 Pu. Deposition temperatures were -72 (Au), -85(Au), and -128(ice). Conclude that element 114 seems to behave like a very volatile metal, with very weak interaction with Au – even weaker than element 112. Most likely gaseous at ambient temperatures.

34. More prosaic, yet vexing chemistry, Rf-Hs Rf

35. Db Expts. complicated and difficult Not well understood

36. Sg “Normal” behavior

37. Bh “the chemistry of bohrium is boring”

38. Hs Chemistry at the 1 pb level

39. Environmental chemistry of the transuranium elements Plutonium is the most important element. Present due to atmospheric testing, satellite re-entry and nuclear power accidents Extremely low concentrations (~10 -18 M) Low levels in soil, sediments, etc.

40. Aqueous environmental chemistry of Pu Hydrolysis Complexation, redox reactions, colloid formation also important. Hydrolyic series An 4+ >AnO 2 2+ > An 3+ > AnO 2 +

41. Complexation