-
350
About 350 B.C
the philospher aritstotle believed in empedocles four element model despite the more recent "atomic" model. -
400
about 400 B.C
another greek, democritus, suggested that matter was made of tiny particles that could not be broken down further . -
450
about 450 B.c
a greeek scholar named empedocles proposed that matter was composed of four elements: earth,air,fire,and water. -
500
A.D 500-1600
do metals grow like plants ripening into gold? many alchemists( combination of philosopher,mystic, magician, and chemist) believed that they did for centuries they performed numerous eperiments attempting to make gold form cheap metals such as iron and lead. -
1650
an english scientist, robert boyle, did not believe in the four-element model -
Late 1700s
joseph priestley was the first person to isolate oxygen scientifically,but he did not know that oxygen is an element. -
1800s
however, dalton's atomic model cannot explain why, on a dry winter day, you get a spark when you touch a metal doorknob. -
1808
by this time it was generally accepted that matter was made of elements: the two models had come togeter. -
1904
J.J. thomson revised the atomic model further, to explain his discovery of very light megative particles, called electrons. -
1911
ernest rutherford, working at mcgill university in montreal,designed an experimeny to test thomson's and nagaoka's models.
