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In this sense atoms were the elementary particles of nature. It was in 1803,
more than 2000 years later, when John Dalton (1766-1844) first provided
Atoms: Dalton
´
s Theory
evidence of the existence of atoms by applying chemical methods. In his
theory, Dalton supported the concept that matter is built of indivisible atoms
of different weights.
All atoms of a specific chemical element are in respect of their mass
(weight) and their chemical behaviour identical.
Furthermore, according to Dalton’s theory, atoms have a spherical shape,
are filled homogeneously with matter and follow strictly the laws of classical
mechanics.
Atoms are able to build compounds keeping their proportion to each other
in the form of simple integers. If these compounds decompose the atoms
involved emerge unchanged from this reaction.