Thorium francium from

Francium-223 is produced from the decay of actinium-227. While the chief decay product is thorium-227 resulting from beta emission, actinium-227 also undergoes alpha emission to an extent of one percent giving francium-223 ... 

The chemical properties span a range similar to the representative elements in the first few rows of the periodic table. Francium and radium are certainly characteristic of alkah and alkaline earth elements. Both Fr and Ra have only one oxidation state in chemical comhina-tions and have little tendency to form complexes. Thallium in the 1+ oxidation state has alkah-like properties, but it does form complexes and has extensive chemistry in its 3+ state. Similarly, lead can have alkaline earth characteristics, hut differs from Ra in forming complexes and having a second, 4+, oxidation state. Bismuth and actinium form 3+ ions in solution and are similar to the lanthanides and heavy (Z > 94) actinides. Thorium also has a relatively simple chemistry, with similarities to zirconium and hafiuum. Protactinium is famous for difficult solution chemistry it tends to hydrolyze and deposit on surfaces unless stabilized (e.g., by > 6 M sulfuric acid). The chemistry of uranium as the uranyl ion is fairly simple, hut... 

Most of the elements found in nature have several isotopes. Elements with atomic number 83 (bismuth) and lower have at least one stable isotope, although some are also radioactive and unstable. From element number 84 (polonium) and upwards, all the elements lack stable isotopes. The nine elements 84-92 are called naturally occurring radioactive elements. They are polonium, astatine, radon, francium, radium, actinium, thorium, protactinium and uranium. They are all treated in this chapter. There are also an additional two radioactive elements, number 43 technetium and 61 promethium. However, they have been described in Chapter 28 Technetium and Chapter 17 Rare earths, respectively. 

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