1700---1800


 * John Dalton



Born:** 6 September 1766
 * Died:** 27 July 1844

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He is best known for his pioneering work in the development of modern ATOMIC THEORY!!!!



"each chemical element is composed of a unique type of atom, and that the atoms differed by their masses. He devised a system of chemical symbols and, having ascertained the relative weights of atoms, arranged them into a table. In addition, he formulated the theory that a chemical combination of different elements occurs in simple numerical ratios by weight, which led to the development of the laws of definite and multiple proportions." He then determined that compounds are made of molecules, and that molecules are composed of atoms in definite proportions. Thus, atoms determine the composition of matter, and compounds can be broken down into their individual elements

THE MOST IMPORTANT THING IN CHEMISTRY!!!!!!!




 * Joseph Black

**


 * 1728 - 1799**

[|http://www.chem.gla.ac.uk/~alanc/dept/black.htm]

Remembered primarily for his work with specific and latent heats as well as his discovery if carbon dioxide.

During the early Glasgow years (1750-52) that it seems Black began his work on the chemistry of "magnesia alba" (a basic magnesium carbonate), which he later submitted for his MD thesis in Edinburgh, and which includes the discovery of what we now call carbon dioxide - he called it "fixed air". These experiments involved the very first careful gravimetric (weight) measurements on changes brought about when heating magnesia alba (with release of CO2) and reacting the products with acids or alkalis. This foreshadowed Lavoisier's work, and laid the foundation for modern chemistry. (Because this work was submitted for a medical degree, Black also felt obliged to include a section on magnesia alba as a purgative and antacid.)


 * Antoine Lavoisier**




 * Born:** in Paris on August 26, 1743
 * Died:** 8 May 1794

[|http://cti.itc.virginia.edu/~meg3c/classes/tcc313/200rprojs/lavoisier2/home.html]

A French nobleman prominent in the histories of biology and Chemistry. He stated the first version of the Law of conservation of mass. recognized and named hydrogen in 1783 as well as Oxygen in 1778. He abolished the Phlogiston theory, helped construct the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature. He discovered that, although matter may change its form or shape, its mass always remains the same. "Lavoisier's researches included some of the first truly quantitative chemical experiments. He carefully weighed the reactants and products in a chemical reaction, which was a crucial step in the advancement of chemistry. He showed that, although matter can change its state in a chemical reaction, the total mass of matter is the same at the end as at the beginning of every chemical change. Thus, for instance, if water is heated to steam, if salt is dissolved in water or if a piece of wood is burned to ashes, the total mass remains unchanged. His experiments supported the law of conservation of mass, which Lavoisier was the first to state."