Period (periodic table) eighth period. Period (periodic table) A period in the periodic table is a horizontal row. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law. For example, the alkali metals lie in the first column (group 1) and share similar properties, such as high reactivity and the tendency to lose one electron to arrive at a noble-gas electronic configuration. As of
Alternative periodic tables quantum numbers of the electron configuration, hence it has a four-dimensional base. In Theodor Benfey's periodic table (1964), the elements form a two-dimensional spiral, starting from hydrogen, and folding their way around two peninsulars, the transition metals, and lanthanides and actinides. A superactinide island is already slotted in. The Chemical Galaxy (2004) is organized in a similar way. Timothy Stowe's physicist's periodic table is three-dimensional with the three axes representing the principal quantum number, orbital quantum number, and orbital magnetic quantum number. Helium is again a group 2 element. Paul Giguère's 3-D periodic table consists of 4 connected billboards with