-
200
atoms
A greek democritus suggested that matter is made up of tiny particles that can not be broken down further -
350
about 350 B.C.
The Philosopher Aristotle believed in Empedocles "four elements" model despite the more recent "atomic" model -
450
about 450 B.C.
a greek scholar named Empedocles proposed that matter was composed of four elements Water,Fire.Air and Earth. these elements mixed togather in different proportions to yield diffrent substances. -
500
A.D. 500-1600
Many alchemists believed that they did. ( combination of philosopher, mystic, magician and chemist. -
1650
An english scientist , Robert Boyle, did not belive in the four elements model. He made a new definition for the word element. -
late 1700s
Joseph Priestly was the first person to isolate oxygen scientifically, but he didnt know that oxygen is a element. that fact was recognized ny Antoine Lavoisier. -
1800s
Daltons atomic model cannot explain why, on a dry winter day, you get a spark when you touch a metal doorknob. ( chargeg an ekectricity that may build up an object ) -
1808
by this time it was generally accepted that matter was made of elements : the two models have come togather -
1904
J.J. thomson revised that atomic model further: to explane his discovery to very light negative particles , called electrons. -
1911
Ernest Rutherford working at McGill university in montreal, designed an experiment to test Thomson's and Nagaoka's model.
