Kindly Give a brief description of "Telluric Helix". With diagrams and illustrations.
The French geologist , Alexandre-Émile Béguyer de Chancourtois(1820-1886) was the first person to make use of atomic weights to produce a classification of periodicity. He drew the elements as a continuous spiral around a metal cylinder divided into 16 parts. The atomic weight of oxygen was taken as 16 and was used as the standard against which all the other elements were compared. Tellurium was situated at the centre, prompting vis tellurique, or telluric screw.
Chancourtois' original formulation includes elements in their correct places, selected compounds and some elements in more than one place. The helix was an important advance in that it introduced the concept of periodicity, but it was flawed. The formulation was rediscovered in the 1889 (P. J. Hartog, "A First Foreshadowing of the Periodic Law" Nature 46, 186-8 (1889)), and since then it has appeared most often in a simplified form that emphasizes the virtues and eliminates its flaws. [Thanks to CG for this info.]