Periodic table observed that carbon often has four other atoms bonded to it. Methane, for example, has one carbon atom and four hydrogen atoms. This concept eventually became known as valency; different elements bond with different numbers of atoms. In 1862, Alexandre-Emile Béguyer de Chancourtois, a French geologist, published an early form of periodic table, which he called the telluric helix or screw. He was the first person to notice the periodicity of the elements. With the elements arranged in a spiral on a cylinder by order of increasing atomic weight, de Chancourtois showed that elements with similar properties seemed to occur
Extended periodic table (detailed cells) Extended periodic table (detailed cells) This is a large version of the extended periodic table of the chemical elements. For the natural isotopic composition of each element it shows "name", "atomic number", "symbol", "standard atomic weight" (or atomic weight) and a link to the element's isotopes. It also has, by keyed markings, a notification of "occurrence", "state of matter" and "metallic character". It is named "extended" because it shows elements that are theoretical only (in period 8), and "large" means that the table might exceed page width. The presentation is wide which means that there are no table parts separated