Block (periodic table) the s-block, with its outer (and only) electrons in the 1s atomic orbital, although its chemical properties are more similar to the p-block noble gases due to its full shell. In addition to the blocks listed in this table, there is a hypothetical g-block which is not pictured here. The g-block elements can be seen in the expanded extended periodic table. Lanthanum and actinium are placed under scandium and yttrium to reflect their status as d-block elements, as they have no electrons in the 4f and 5f orbitals, respectively, while lutetium and lawrencium do. The s-block is on the left
Extended periodic table (detailed cells) the seventh period, as they are calculated to have an additional so-called g-block, containing 18 elements with partially filled "g-orbitals" in each period. An eight-period table containing this block was suggested by Glenn T. Seaborg in 1969. It is not known how many elements are physically possible, if period 8 is complete, or if there is a period 9. Chemical series information for elements past hassium (except copernicium), is hypothetical and based on periodic trends. Superheavy elements may not exist, and may not follow the order of this table even if they do. Extended periodic table (detailed cells) This is