Today, the periodic table is organized by atomic number, which is the number of protons in the nucleus. But they didn’t know about protons then, so they organized everything by atomic weight.

The periodic table of elements classifies elements according to patterns in properties. Elements in a group, or family, have similar properties ...

150 years ago, Russian chemist Dmitrii Mendeleev created the periodic table of the elements, revolutionizing chemistry. Skip to content. Subscribe or renew today ...

The periodic table of elements, devised by Russian chemist Dmitri Mendeleev, is a two-dimensional array of the chemical elements, ordered by atomic number and arranged 18 across by orbitals.

In December 2015, IUPAC made the first of several broadcasts: Four elements, Nos. 113, 115, 117 and 118, met the criteria for inclusion in the periodic table.

The elements were placed in the periodic table’s seventh row, which is above the row of lanthanides and the row of actinides. In the 1980s and 1990s, Roberto noted, scientists at the GSI Helmholtz ...