![]() Atoms belonging to an element can enter or leave a molecule of a chemical compound during a chemical reaction, but their total mass in the system will remain unchanged. The English chemist John Dalton (1766-1844) proposed his principles of atomic theory in 1803, suggesting that all elements are composed of tiny, indestructible particles called atoms, all of which are equal and weigh exactly the same. Substances simples métalliques oxydables et acidifiables Substances simples non-métalliques oxydables et acidifiables Lavoisier's table of simple substances Substances simples qui appartiennent aux trois règnes et qu'on peut regarder comme les éléments des corps Lavoisier's name is inextricably linked with the very foundations on which modern science lies: it is considered that he did for chemistry what Isaac Newton (1642.-1727.) did for physics. Ironically, given his enormous contribution to the overthrow of the phlogiston theory, he listed light and heat among the elements. His table of elements, simple substances that cannot be further split and from which all other matter was formed, contained 33 elements divided into four groups: gasses, non-metals, metals, and soil (Table 1). ![]() He clarified the distinction between elements and compounds, and also assisted in developing the modern system of chemical terminology. In this classic work, Lavoisier made sure to give concise explanations of both his own work, and the work of his predecessors. The first table of simple chemical substances was presented in 1789 by the french chemist Antoine-Laurent Lavoisier (1743-1794) in his book "Traité Élémentaire de Chimie ". Complex bodies are made from elements and can be reduced to those elements through chemical analysis. Without going into the nature and number of elements, Boyle defined each element as a simple substance, a building block from which more complex things are made. This was done in 1661 by the "father of modern chemistry ", English-Irish chemist and naturalist Robert Boyle (1627-1691), in his book "The Sceptical Chymist". It took almost 2000 years for someone to seriously attack Aristotle's theory of the four elements and the somewhat more contemporary three alchemical principles (mercury, sulphur, and salt). The only thing kept from the Greek idea of element was that each element has characteristic properties. ![]() This appeared to be quite reasonable since burnt wood decomposed into three elements: water, air, and earth. A hundred years later Aristotle (384-322) embraced his idea and added that, each of the four elements has four basic properties: hot, cold, dry, and wet. Empedocles (490-430) believed that all matter was made up of four elements: air, earth, fire, and water, and that by mixing those elements in various ratios one could create every substance found in nature. Tales believed that this element was water, his student Anaximander thought it was air, and Heraclites speculated it was fire. The old Greek philosophers Tales (624-546), Anaximander (610-546), and Heraclites (540-480) claimed that all matter was made up of one fundamental principle - or element. Aristotle's elements and their properties → Download high quality image
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