Thulium discovery

If attention is now turned to the heavier elanents as shown in the model, it is seen that the five unknown elements eka-caesimn, e -manganese 1, eka-mmiganese 2 (dwi-manganese), eka-iodine, and eka-neodymium, have odd atomic numbers. (There is some doubt as to the discovery of thulium 2.) Not only are the unknown elements odd numbered, but among the radio-active elements, if the most stable isot( of each element is used for the comparison, the odd numbered elemente are much less stable than the adjacent elements of even number. 

In 1961 Hayes and Twidell (8) found that if calcium fluoride crystals containing trivalent thulium were irradiated with x-rays, some of the thulium was converted to the divalent state. This discovery was the first of many in the study of dilute solutions of divalent rare earth ions. Most workers prefer to study the alkaline earth fluorides since these materials are stable with respect to air and have more attractive mechanical properties than the alkaline earth chlorides, bromides, and iodides. Enough work has been carried out in these softer materials to show that reactions similar to those in the fluorides do occur. 

Thulium was given its name in honor of the earliest name for Scandinavia, Thule. The element was discovered and named by Swedish chemist Per Teodor Cleve (1840-1905) in 1879. Cleve made his discovery while studying the mineral erbia. Thulium was one of the many new elements found in a black rock discovered outside the town of Ytterby, Sweden, in 1787. The complete analysis of that rock took more than 100 years. In the process, nine new elements, including thulium, were discovered. 

In 1879 the chemical individuality of erbium freed from impurities was proven beyond any doubt and that year rather than 1843 can be considered to be the date of its discovery. Thulium turned out to be pure as well, but holmium s real birth was still ahead. So the yttrium tree branched copi-... 

Discovery During 1878-79, PerT. Cleve in Uppsala discovered that erbium contained two other elements. He named them thulium after the old Roman name Thulia for the Furthest North and holmium after Stockholm. Delafontaine and Soret in Switzerland had in fact found lines of a foreign element during the spectral analysis of erbium in 1878. This element, erbium-X or element-X, appeared to be identical with holmium. In tables of discoverers Delafontaine and Soret are mentioned alongside Cleve. 

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