This form of periodic table is more congruent with the order in which electron shells are filled, as shown in the accompanying sequence in the left margin (read from top to bottom, left to right). The placement of helium (a noble gas) above beryllium (an alkaline earth metal) ordinarily attracts strong criticism from chemists.
Column counts are columns only that contain elements. "Compact cells" denote cells with element symbol only, have navbox style and the table fits basic wiki page width (1024×768). "Large cells" have more data, and may cause page width excess (scroll bar added). "Extended" periodic tables are about theoretical periods 8 and higher (element 119 and higher).