History of Atomic Theory

John Dalton is the originator of the atomic theory. He is famous for his theory that revived the term "atom". In the essay book entitled New System of Chemical Philosophy he managed to formulate terms of atoms around the year 1803. John Dalton lived during 1766-1844. He states that matter is composed of atoms that can not be subdivided. Each element consists of atomatom with identical properties and mass, and compounds are formed when atoms of different elements joined in a fixed composition.

John Dalton was the British scientist who at the beginning of the 19th century to the atomic hypothesis put forward in the arena of science. With this act, he presents the key ideas that enable major advances in chemistry since then.

Although the terminology is a bit different from what we use now, Dalton clearly put forward the concept of atoms, molecules, elements and chemical compounds. He was clear that although the total number of atoms in the world so much, but the number of different types of different kind of small. (The book originally recorded 20 elements or groups of atoms; currently a little over 100 elements are known).

Although different types of atoms of different weight, Dalton remains found by two atoms of the same group is the same in all qualities, including "mass" (the quantity of material in an object measured by resistance to change in motion). Dalton include in his list that records the relative weight of the various types of atoms are different, the first ever prepared a list of people and is the key to any quantitative theory of the atom.

Dalton also explained clearly that each of the two molecules of the same chemical combination consists of a combination of similar atoms. (For example, each molecule "nitrous oxide" (N2O) consists of two nitrogen atoms and one oxygen atom). From this particular chemical combination to form something no matter how prepared or where acquired always consists of the same elements in the same proportion that fully weight. This is the "law of definite proportions," which has been found experimentally by Joseph Louis Proust first few years.

Once convinced how Dalton presents the theory, so that within twenty years he has been accepted by the majority of scientists. Furthermore, chemical experts who follow the program proposed by the textbook 4: determine exactly the relative atomic weight; combined chemical analysis of weight; determine the right combination of atoms that make up each group of molecules that have characteristics in common. The success of this program, of course, incredible.

Results reflection refine Dalton's atomic theory of Democritus. Shadow Dalton and Democritus was that the object was shaped solid. In hindsight Dalton argued postulatnya about atoms.

a) Each element consists of particles with atoms ketch called

b) Atoms of the same element) Atoms of different elements have different properties

c) Atoms of an element can not be converted into atoms of another element with the chemical reaction, atoms can not be destroyed and atokan

d) Atoms can combine to form atoms called molecules combined

e) In the compound, the ratio of the mass of each element is fixed.

Dalton's atomic theory began to arouse interest in the study of atomic models. However, Dalton's atomic theory has shortcomings, which can not explain a solution to conduct electrical current. How could the ball solid dapatmenghantarkan electricity when electricity is electrons moving. Meaning there are other particles that can conduct electric current.