The modern periodic table is a must have in a chemistry class. It is more than a tabular organisation of chemical substances, but through it, reactivity among elements is predicted and other ranges of chemical properties are analysed. The periodic table arranges the elements by their atomic numbers and periodic properties. But scientists took over a century to assemble the elements that make up this table. The whole game started in 1789 during the French revolution when a French chemist, Antoine Lavoisier, tried grouping the chemical elements as metals and non-metals. Forty years later, a German physicist, Johann Wolfang Dobereinner, observed a range of similarities in physical and chemical properties of some elements. He then arranged them in groups of three in increasing atomic weight, hence, calling them triads. In 1860, at the first international conference in Karlsruhe, Germany, a revised list of elements was published. The conference concluded an arrangement with increasing atomic mass. British chemist John Newlands was the first to arrange the elements into a periodic table with increasing order of atomic masses. He then arranged eight elements with similar properties and called them the law of octaves, but left no gaps undiscovered. The undiscovered gap gave space to a Russian chemist, Dimitri Mendeleev Ivanovic, in 1869, who created the framework that became the modern periodic table. Mendeleev even left gaps for elements that were yet to be discovered. He then predicted the names of the undiscovered elements. An element that was below aluminium, he named it “Eka-aluminium” meaning under aluminium, and that element was later on discovered as gallium. A German chemist, Lothar Meyer, produced another version of the periodic table which was similar to Mendeleev’s but did not explain the properties of the yet to be discovered elements. The Royal Society of London awarded the Davy Medal in 1882 to both Mendeleev and Meyer and the periodic table gained a universal recognition since then. In 1995, the 101st element was named Mendelevium in Mendeleev’s honour. UNESCO named 2019 the International Year of the Periodic Table to mark the 150th anniversary of Mendeleev’s publication. The use of a periodic table is able to solve the problems in health, agriculture, environment, education and technology.
