![]() The four predicted elements lighter than the rare-earth elements, eka- boron ( Eb, under boron, B, 5), eka- aluminium ( Ea or El, under Al, 13), eka- manganese ( Em, under Mn, 25), and eka- silicon ( Es, under Si, 14), proved to be good predictors of the properties of scandium (Sc, 21), gallium (Ga, 31), technetium (Tc, 43), and germanium (Ge, 32) respectively, each of which fill the spot in the periodic table assigned by Mendeleev. (as located in the modern periodic table) But current official IUPAC practice is to use a systematic element name based on the atomic number of the element as the provisional name, instead of being based on its position in the periodic table as these prefixes require. Sometimes, eka- is still used to refer to some of the transuranic elements, for example, eka- radium for unbinilium. Before the discovery, francium was referred to as eka-caesium, and astatine as eka-iodine. ![]() The eka- prefix was used by other theorists, and not only in Mendeleev's own predictions. For example, germanium was called eka-silicon until its discovery in 1886, and rhenium was called dvi- manganese before its discovery in 1926. To give provisional names to his predicted elements, Dmitri Mendeleev used the prefixes eka- / ˈ iː k ə-/, dvi- or dwi-, and tri-, from the Sanskrit names of digits 1, 2, and 3, depending upon whether the predicted element was one, two, or three places down from the known element of the same group in his table. He named them eka-boron, eka-aluminium, eka-silicon, and eka-manganese, with respective atomic masses of 44, 68, 72, and 100. When Mendeleev proposed his periodic table, he noted gaps in the table and predicted that then-unknown elements existed with properties appropriate to fill those gaps. Dmitri Mendeleev published a periodic table of the chemical elements in 1869 based on properties that appeared with some regularity as he laid out the elements from lightest to heaviest.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |