<P> Dalton also proposed a modern atomic theory in 1803 which stated that all matter was composed of small indivisible particles termed atoms , atoms of a given element possess unique characteristics and weight , and three types of atoms exist : simple ( elements ) , compound ( simple molecules ) , and complex ( complex molecules ) . In 1808 , Dalton first published New System of Chemical Philosophy ( 1808 - 1827 ) , in which he outlined the first modern scientific description of the atomic theory . This work identified chemical elements as a specific type of atom , therefore rejecting Newton 's theory of chemical affinities . </P>
<P> Dalton also proposed a modern atomic theory in 1803 which stated that all matter was composed of small indivisible particles termed atoms , atoms of a given element possess unique characteristics and weight , and three types of atoms exist : simple ( elements ) , compound ( simple molecules ) , and complex ( complex molecules ) . In 1808 , Dalton first published New System of Chemical Philosophy ( 1808 - 1827 ) , in which he outlined the first modern scientific description of the atomic theory . This work identified chemical elements as a specific type of atom , therefore rejecting Newton 's theory of chemical affinities . </P>
when did the development of atomic theory begin
when did the development of atomic theory begin
1803
1803