Production, handling, and chemistry of the elements berkelium, californium, einsteinium and fermium. Pt. 2

Elements with proton numbers 97 to 100 - berkelium, californium, einsteinium and fermium - are the heaviest elements to be prepared in weighable amounts, today and probably also in future. This allows the preparation of solid compounds in the ultramicro level, presently at least with 249Bk, 249Cf and 253Es, even if the still built-up pg-amounts of 257Fm did not yet allow such investigations. All studies in the solid state and in solution have demonstrated that these elements are typical actinide (An) elements, possessing localized 5fn-electrons. The presently known metals have typical lanthanide metal crystal structures - in strong contrast to the light actinides with their itinerant electrons. The most stable oxidation state is An(III), whereas An(IV) shows decreasing and An(II) increasing stability with increasing proton number. Handling of the high radioactive heavier actinides in macroscopic amounts, even in the ultramicro level, requires special methods, especially for relatively short-lived 253Es (t1/2 = 20 d). The ingrowth of 249Bk daughter and 249Cf granddaughter into halides of parent 253Es shows that the oxidation state of the parent is retained by the granddaughter species, e.g., 253EsBr2 → (249BkBr2) → 249CfBr2. This paper will give a short and updated review on the properties of these exotic elements. (orig.)