Periodic table
Russian chemistry professor Dmitri Mendeleev and German chemist Julius Lothar Meyer independently published their periodic tables in 1869 and 1870, respectively. Mendeleev's table was his first published version; that of Meyer was an expanded version of his (Meyer's) table of 1864. They both constructed their tables by listing the elements in rows or columns in order of atomic weight and starting a new row or column when the characteristics of the elements began to repeat.
Scandium
Dmitri Mendeleev, who is referred to as the father of the periodic table, predicted the existence of an element "ekaboron", with an atomic mass between 40 and 48 in 1869. Lars Fredrik Nilson and his team detected this element in the minerals euxenite and gadolinite in 1879. Nilson prepared 2 grams of scandium oxide of high purity. He named the element scandium, from the Latin "Scandia" meaning "Scandinavia". Nilson was apparently unaware of Mendeleev's prediction, but Per Teodor Cleve recognized the correspondence and notified Mendeleev.