Andreas von Antropoff his Periodic Table in the article ""Eine neue Form des periodischen Systems der Elemente"" in the "Zeitschrift für angewandte Chemie" in 1926. The periodic table is regularly numbered from 1 - Hydrogen to 118 - Oganesson, with "each number representing the number of protons stored within an atom's nucleus in a satisfying balance" compared to most other contemporary tables. In addition he placed the theoretical "Element zero", which had "been a matter of conjecture for nearly a century" atop his periodic table and called it Neutronium. His periodic table was in widespread use in German schools until 1945 and soon
Extended periodic table recent discovery being that of tennessine in 2010. As some superheavy elements were predicted to lie beyond the seven-period periodic table, an additional eighth period containing these elements was first proposed by Glenn T. Seaborg in 1969. This model continued the pattern in established elements and introduced a new g-block and superactinide series beginning at element 121, raising the number of elements in period 8 compared to known periods. These early calculations failed to consider relativistic effects that break down periodic trends and render simple extrapolation impossible, however. In 1971, Fricke calculated the periodic table up to "Z" = 172,