Great Chemists

Great ChemistsWhat would life be like if nobody had ever studied chemistry? Everything is made of chemicals.Youare made of chemicals. So is your dog. So is your desk. So is thesun. Drugs are chemicals. Food is made from chemicals.Many of the changes you observe in the world around you are caused by chemical reactions. Examples include changingcolors of leaves,cooking foodandgetting clean.Knowing some chemistry can help you make day to day decisions that affect your life. Can I mix thesehousehold chemicals? What aresafe mosquito repellents? Will mybottled waterexpire?

Dmitri Ivanovich Mendeleev (8 February 1834 2 February 1907) was a Russianchemistand inventor. He formulated the Periodic Law, created his own version of theperiodic tableofelements, and used it to correct the properties of some already discovered elements and also to predict the properties of eight elements yet to be discovered.

By adding additional elements following this pattern, Dmitri developed his extended version of the periodic table.[On 6 March 1869, Mendeleev made a formal presentation to theRussian Chemical Society, entitledThe Dependence between the Properties of the Atomic Weights of the Elements, which described elements according to bothatomic weightandvalence. This presentation stated thatThe elements, if arranged according to their atomic weight, exhibit an apparent periodicity of properties.Elements which are similar regarding their chemical properties have atomic weights which are either of nearly the same value (e.g., Pt, Ir, Os) or which increase regularly (e.g., K, Rb, Cs).The arrangement of the elements in groups of elements in the order of their atomic weights corresponds to their so-called valencies, as well as, to some extent, to their distinctive chemical properties; as is apparent among other series in that of Li, Be, B, C, N, O, and F.The elements which are the most widely diffused have small atomic weights.The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound body.We must expect the discovery of many yet unknown elementsfor example, two elements, analogous to aluminium andsilicon, whose atomic weights would be between 65 and 75.Certain characteristic properties of elements can be foretold from their atomic weights.

Marie Skodowska-Curie(7 November 1867 4 July 1934) was aPolish and naturalized-Frenchphysicistandchemistwho conducted pioneering research onradioactivity. She was thefirst woman to win a Nobel Prize, the first person and only woman towin twice, the only person to win twice in multiple sciences, and was part of the Curie family legacy offive Nobel Prizes. She was also the first woman to become a professor at theUniversity of Paris, and in 1995 became the first woman to be entombed on her own merits in thePanthonin Paris.

Her achievements included a theory ofradioactivity(a term that she coined), techniques for isolating radioactiveisotopes, and the discovery of two elements,poloniumandradium. Under her direction, the world's first studies were conducted into the treatment ofneoplasms, using radioactive isotopes. She founded theCurie Institutes in Parisandin Warsaw, which remain major centres of medical research today. DuringWorld War I, she established the first military field radiological centres.While a French citizen, Marie Skodowska Curie (she used both surnames)never lost her sense ofPolish identity. She taught her daughters thePolish languageand took them on visits to Poland.She named the firstchemical elementthat she discovered polonium, which she isolated in 1898 after her native country.

Louis Pasteur (18221895)Famous For:The process of Pasteurization and creation of Vaccines for Rabies and AnthraxIn addition to developing the process of Pasteurization, Louis Pasteur discovered the assymetrical molecular structure on certain crytals. He made some of the earliest vaccines for rabies and anthrax, and the reduction of a bacterial infection in what is known as puerperal fever.

Pasteur was responsible for crushing the doctrine ofspontaneous generation. He performed experiments that showed that without contamination, microorganisms could not develop. Under the auspices of theFrench Academy of Sciences, he demonstrated that in sterilized and sealed flasks nothing ever developed, and in sterilized but open flasks microorganisms could grow. This experiment won him the Alhumbert Prize of the academy

Antoine Lavoisier (17431794)Famous For:Being the Father of Modern ChemistryLavoisier was able to show the relationship between oxygen and metal, resulting in rust. He also was able to show the role of oxygen in plant respiration and in animals. It was he who showed that water was made of hydrogen and oxygen, and that air was composed mainly of oxygen and nitrogen in its gaseous state.

It is generally accepted that Lavoisier's great accomplishments in chemistry largely stem from his changing the science from a qualitative to a quantitative one. Lavoisier is most noted for his discovery of the roleoxygenplays incombustion. He recognized and namedoxygen(1778) andhydrogen(1783) and opposed thephlogiston theory. Lavoisier helped construct themetric system, wrote the first extensivelist of elements, and helped to reformchemical nomenclature. He predicted the existence ofsilicon(1787)[5]and was also the first to establish that sulfur was an element (1777) rather than a compound.[6]He discovered that, although matter may change its form or shape,its mass always remains the same.