Period 6 element Period 6 element A period 6 element is one of the chemical elements in the sixth row (or "period") of the periodic table of the elements, including the lanthanides. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The sixth period contains 32 elements, tied for the most with period 7, beginning with caesium and ending with radon. Lead is currently
Extended periodic table chemically active. Its chemical behaviour is expected to be similar to uranium and neptunium, as further ionisation past the +6 state (corresponding to removal of the 6g electrons) is likely to be unprofitable; the +4 state should be most common in aqueous solution, with +5 and +6 reachable in solid compounds. The number of physically possible elements is unknown. A low estimate is that the periodic table may end soon after the island of stability, which is expected to center on "Z" = 126, as the extension of the periodic and nuclides tables is restricted by the proton and the