There are many periodic tables with layouts other than that of the common or standard form. Within 100 years of the appearance of Mendeleev's table in 1869 it has been estimated that around 700 different periodic table versions were published. As well as numerous rectangular variations, other periodic table formats have included, for example, circular, cubic, cylindrical, edificial (building-like), helical, lemniscate, octagonal prismatic, pyramidal, separated, spherical, spiral, and triangular forms. Such alternatives are often developed to highlight or emphasize chemical or physical properties of the elements that are not as apparent in traditional periodic tables.
A popular alternative layout is that of Theodor Benfey (1960). The elements are arranged in a continuous spiral, with hydrogen at the center and the transition metals, lanthanides, and actinides occupying peninsulas.
Most periodic tables are two-dimensional however three-dimensional tables are known to as far back as at least 1862 (pre-dating Mendeleev's two-dimensional table of 1869). More recent examples include Courtines' Periodic Classification (1925), Wringley's Lamina System (1949), Giguère's Periodic helix (1965) and Dufour's Periodic Tree (1996). Going one better, Stowe's Physicist's Periodic Table (1989) has been described as being four-dimensional (having three spatial and one colour dimension).
The various forms of periodic tables can be thought of as lying on a chemistry–physics continuum. Towards the chemistry end of the continuum can be found, as an example, Rayner-Canham's 'unruly' Inorganic Chemist's Periodic Table (2002), which emphasizes trends and patterns, and unusual chemical relationships and properties. Near the physics end of the continuum is Janet's Left-Step Periodic Table (1928). This has a structure which shows a closer connection to the order of electron-shell filling and, by association, quantum mechanics. Somewhere in the middle of the continuum is the ubiquitous common or standard form of periodic table. This is regarded as better expressing empirical trends in physical state, electrical and thermal conductivity, and oxidation numbers, and other properties easily inferred from traditional techniques of the chemical laboratory.
|Janet left-step periodic table|
|3d 4p 5s||Sc||Ti||V||Cr||Mn||Fe||Co||Ni||Cu||Zn||Ga||Ge||As||Se||Br||Kr||Rb||Sr|
|4d 5p 6s||Y||Zr||Nb||Mo||Tc||Ru||Rh||Pd||Ag||Cd||In||Sn||Sb||Te||I||Xe||Cs||Ba|
|4f 5d 6p 7s||La||Ce||Pr||Nd||Pm||Sm||Eu||Gd||Tb||Dy||Ho||Er||Tm||Yb||Lu||Hf||Ta||W||Re||Os||Ir||Pt||Au||Hg||Tl||Pb||Bi||Po||At||Rn||Fr||Ra|
|5f 6d 7p 8s||Ac||Th||Pa||U||Np||Pu||Am||Cm||Bk||Cf||Es||Fm||Md||No||Lr||Rf||Db||Sg||Bh||Hs||Mt||Ds||Rg||Cn||Uut||Fl||Uup||Lv||Uus||Uuo||Uue||Ubn|
|left; font-size: 90%">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.|
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