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610 BC) thought that the basic substance was a substance that he called aperion, whose quality was indefinite and whose quantity was infinite.įor Anaximenes (585-525 BC), the most basic (indivisible) substance was air.Īristotle (384-322 BC) thought that the seven known metals came from the earth, air, fire, and water and that each body was composed of mixtures of these four substances in various proportions.

Thales (624-546 BC) considered water the most basic substance. The idea that fire, air, water, and earth are essential elements dominated human thought for nearly 2000 years.

Again, with the help of fire, alloys could be made by mixing metals. In this way, pure metals began to be obtained from ores in compound form. The smelting of metal ores by fire is one of the greatest revolutions in history. The history of the discoveries of the elements is also the history of developments in physics and chemistry.īefore BC, only seven elements were known: gold, silver, copper, lead, tin, iron, and mercury. The periodic table is the arrangement of elements according to their atomic numbers so that elements with similar properties appear in the same vertical column or group. Many new elements were discovered, while others were synthesized artificially. The periodic table has undergone extensive changes over time since Mendeleev and Moseley originally developed it. Although helium is found on earth, it was first discovered by observing the sun. The country of Argentina is named after the element silver (symbol Ag), which is Argentum in Latin. The only letter not found in the periodic table is the letter J. There are probably no more than a few ounces on earth at any given time. Carbon is an essential element for the existence of life. Using the table, Mendeleev could accurately predict the properties of many elements before they were discovered. The periodic table was proposed by the Russian chemist Dmitry Mendeleev in 1869.