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Q. What is the basis of a periodic table?
A. Mendeleev, introducing his periodic table to the Russian Chemical Society in 1869, began by explaining, "The elements, if arranged according to their atomic weights, exhibit an evident periodicity of properties." Later "weights" were replaced by "masses", which have been replaced by "atomic numbers." In more general terms, the 2008 Wikipedia guide is "..certain properties of elements repeat periodically when arranged by atomic number."
Details of answer;
the periodic table is one of the most powerful icons in science; a single document that captures the essence of chemistry in an elegant pattern.
Combinations of 26 letters make up every word in the English language.
Similarly, all material things in the world are composed of different combinations of about 100 different elements. An element is a substance that cannot be broken down into simpler substances through ordinary chemistry--it is not destroyed by acids, for example, nor changed by electricity, light, or heat.
Discovery of the 92 natural elements is one of the greatest achievements of human intellectual curiosity.
Although philosophers in the ancient world had a rudimentary concept of elements, they were incorrect in identifying water, for example, as one. Today it is common knowledge that water is a compound, whose smallest unit is a molecule.
Passing electricity through a molecule of water can separate it into two atoms of hydrogen and one atom of oxygen, each a separate element.
the ancient concept of elements jibed with today’s in noting that elements had characteristic properties. Just as people not only look different from each other but also interact differently with others, so elements have both physical and chemical properties. Some elements form shiny solids, for example, that react readily and sometimes violently with oxygen and water. The atoms of other elements form gases that scarcely interact with other elements.
When Dmitri Mendeleev, a Siberian professor of general chemistry was unable to find an appropriate textbook he began writing his own. That textbook, written between 1868 and 1870, would provide a framework for modern chemical and physical theory.
Scientists had identified over 60 elements by Mendeleev’s time, and elements were considered the most basic particle of matter. The building blocks of atoms (electrons, protons, and neutrons) were discovered only later. What Mendeleev and chemists of his time could determine, however, was the atomic weight of each element: how heavy its atoms were in comparison to an atom of hydrogen, the lightest element.
Resources;
World of Elements, Elements of the World; Quadbeck-Seeger, the Periodic Table; Scerri, chemeducator.org, aip.org, corrosion-doctors.org
