1 jan 1803 ano - John Dalton

Descrição:

Britain
1803
John Dalton’s most important contribution to science was his theory, that matter is composed of atoms of different weights that combine in simple ratios by weight to make compounds. This theory, which Dalton first advanced in 1803, is the beginning of modern physical science. In 1808 Dalton’s A New System of Chemical Philosophy was published. In this book he listed the atomic weights of a number of known elements relative to the weight of hydrogen. His weights were not entirely accurate but they were the base for the modern periodic table of the elements. John Dalton arrived at his atomic theory through a study of the physical properties of atmospheric air and other gases.His theory states-
1. Elements are made of very tiny particles called atoms 
2. Atoms of a certain element are identical in mass,size and properties 
3. Atoms cannot be created or destroyed 
4. Atoms of different elements combine to form chemical compounds 
5. In chemical reactions atoms are combined, separated or rearranged 