Francium

ATOMIC MASS 223 amu VALENCE OXIDATION STATE -M ( ). NATURAL STATE  

ORIGIN OF NAME In 1939 Marguerite Perey (1909-1975), a French physicist who worked for the Curie institute in Paris, named the newly discovered element after her country—France. 

ISOTOPES There are no stable isotopes of francium found on Earth. All of its 33 isotopes (ranging from Fr-201 to Fr-232) are radioactive therefore, the one with the longest half-life of about 20 minutes (Fr-223) is the one used to determine its atomic weight. Fr-223 is the only radioisotope of francium that is found naturally as a decay product from other unstable elements. 

Energy Levels/Shells/Electrons Orbitals/Electrons 

Not a great deal is known about francium s properties, but some measurements of its most stable isotope have been made. Its melting point is 27°C and its boiling point is 677°C, but its density is unknown. It is assumed to have a +1 oxidation state (similar to all the other alkali metals) 

The element No. 87 has a place of its own in the history of radioactive elements. Though its natural abundance is extremely small it was found originally in nature. But we shall tell its story in detail in the part of the book dealing with artificial elements. This will be better for many reasons. 

The idea of transmutation (transformation) of elements was born in distant times. The idea was upheld by alchemists for their specific aims. But all attempts to achieve transmutation proved futile. As chemistry was developing into an independent full-fledged science and accumulating knowledge of the structure and properties of matter the very feasibility of transformation of elements was questioned. By the end of the 19th century serious scientists ignored this problem though did not dare to refute it definitely. 

But at the very end of the century an event happened which suggested the paradoxical idea that continuous transmutation of elements takes place in nature. This event was the discovery of radioactivity. But only a relatively small part of elements at the very end of the periodic system are subjected to natural transmutation. 

Radioactive transformations are independent of human will. All attempts to affect the course of natural radioactive processes failed. When the nuclear model of atomic structure was formulated it became clear that radioactivity is a nuclear phenomenon. The structural features of nuclei determine the capacity for radioactive decay. 

Rutherford was the first to carry out artificial transmutation of elements. In 1919 he bombarded nitrogen with alpha particles and obtained oxygen atoms. This first in history 

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The table contains vertical groups of elements each member of a group having the same number of electrons in the outermost quantum level. For example, the element immediately before each noble gas, with seven electrons in the outermost quantum level, is always a halogen. The element immediately following a noble gas, with one electron in a new quantum level, is an alkali metal (lithium, sodium, potassium, rubidium, caesium, francium). 

Taking francium as an example, it was assumed that the minute traces of francium ion Fr could be separated from other ions in solution by co-precipitation with insoluble caesium chlorate (VII) (perchlorate) because francium lies next to caesium in Group lA. This assumption proved to be correct and francium was separated by this method. Similarly, separation of astatine as the astatide ion At was achieved by co-precipitation on silver iodide because silver astatide AgAt was also expected to be insoluble. 

Relatively little is known about the chemistry of the radioactive Group I element francium. Ignoring its radioactivity, what might be predicted about the element and its compounds from its position in the periodic table ... 

The isolation and identification of 4 radioactive elements in minute amounts took place at the turn of the century, and in each case the insight provided by the periodic classification into the predicted chemical properties of these elements proved invaluable. Marie Curie identified polonium in 1898 and, later in the same year working with Pierre Curie, isolated radium. Actinium followed in 1899 (A. Debierne) and the heaviest noble gas, radon, in 1900 (F. E. Dorn). Details will be found in later chapters which also recount the discoveries made in the present century of protactinium (O. Hahn and Lise Meitner, 1917), hafnium (D. Coster and G. von Hevesey, 1923), rhenium (W. Noddack, Ida Tacke and O. Berg, 1925), technetium (C. Perrier and E. Segre, 1937), francium (Marguerite Percy, 1939) and promethium (J. A. Marinsky, L. E. Glendenin and C. D. Coryell, 1945). 

Lithium, Sodium, Potassium, Rubidium, Caesium and Francium... 

The alkali metals form a homogeneous group of extremely reactive elements which illustrate well the similarities and trends to be expected from the periodic classification, as discussed in Chapter 2. Their physical and chemical properties are readily interpreted in terms of their simple electronic configuration, ns, and for this reason they have been extensively studied by the full range of experimental and theoretical techniques. Compounds of sodium and potassium have been known from ancient times and both elements are essential for animal life. They are also major items of trade, commerce and chemical industry. Lithium was first recognized as a separate element at the beginning of the nineteenth eentury but did not assume major industrial importance until about 40 y ago. Rubidium and caesium are of considerable academic interest but so far have few industrial applications. Francium, the elusive element 87, has only fleeting existence in nature due to its very short radioactive half-life, and this delayed its discovery until 1939. 

Francium was first identified in 1939 by the elegant radiochemical work of Marguerite Perey who named the element in honour of her native country. It occurs in minute traces in nature as a result of the rare (1.38%) branching decay of Ac in the series ... 

W. A. Hart and O. F. Beumel, Lithium and its compounds, Comprehen.tive Inorganic Chemistry. Vol. 1, Chap. 7, Pergamon Press, Oxford, 1973. T. P. Whaley, Sodium, potassium, rubidium, caesium and francium, ibid.. Chap. 8. 

The six elements adjacent to and following the six inert gases are lithium, sodium, potassium, rubidium, cesium, and francium. These elements have similar chemistries and are called the... 

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