Period 6 element between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods). Lanthanum is a chemical element with the symbol La and atomic number 57. It is the first element in the lanthanide series. It is a soft, ductile, silvery-white metal that tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It is the eponym of the lanthanide series,
Group 3 element be reduced to their elements, meaning that the discovery of a new earth was equivalent to the discovery of the element within, which in this case would have been "yttrium". Until the early 1920s, the chemical symbol "Yt" was used for the element, after which "Y" came into common use. Yttrium metal was first isolated in 1828 when Friedrich Wöhler heated anhydrous yttrium(III) chloride with potassium to form metallic yttrium and potassium chloride. In 1869, Russian chemist Dmitri Mendeleev published his periodic table, which had empty spaces for elements directly above and under yttrium. Mendeleev made several predictions on the