Development of the periodic tableIntroduction:The periodic table is a table that classifies all known chemical elements in order of their atomic numbers. During the 1600s, vast knowledge about the properties of elements and their compounds was discovered, and by 1869, 63 elements had been discovered. As more elements were discovered, scientists began to recognize similarities between their properties and devise means of classification. This is how the periodic table of elements was created. The current periodic table contains 117 elements, but more could still be discovered. The elements of the periodic table are classified into groups, periods and blocks. Groups refer to elements with similar properties and make up the vertical columns of the table. The dots are the horizontal lines and illustrate the number of valence electrons each element has (how many electrons are in the element's outer shell). The position an element is in on the array allows a scientist to easily judge its properties, reactivity, and similarities to other elements. Dmitri Mendeleev's Periodic Table: Dmitri Mendeleev, a Russian scientist, is said to be the father of the periodic table. In 1947, Mendeleev, while working on a textbook, began to organize the 63 elements known at the time into groups with similar properties. Mendeleev struggled to classify certain alkali metals and metals, and while trying to find a way to classify them, he began to notice that the properties and atomic weights of halogens and alkali metals shared similar patterns. He then began to study the extensions of these models within the other elements. Mendeleev created a map for each of the known elements which appear middle of paper ... the first version of atomic theory, which later allowed John Dalton to develop atomic theory to create a method of discerning atomic weight, has was crucial in the development of the table. It was by finding the atomic weight of the elements as well as classifying their properties that Mendeleev was able to create his periodic table and discern possible new elements. The work of JJ Thompson and James Chadwick was also important in creating the "finalized" version of the periodic table. painting. The discovery of the electron, and later the proton and neutron, not only allowed scientists to begin trying to create a detailed model of the atom, but also allowed Henry Moseley to notice the patterns of protons between the elements and thus create a more precise interpretation of the atom. Mendeleev's table classifying elements by atomic number rather than atomic weight.