-
200
Atoms
Another greek person, Democritus, suggested that matter was created of tiny particles that could not be broken down further. He called thoughs particles "Atoms" after the greek word atomos. -
350
About 350 B.C
The philosopher aristotle believed in Empedocles "four element idea" although the more recent "atomic" model. -
Period: 500 to
500-1600
Do metals grow like plants ripening into gold? Many alchemists believed that they did. For centuries they performed numerous experiments attempting to make gold from cheap metals such as iron or lead. -
1650
An english scientist, Robert boyle, did not believe, nor had faith in the four element model. He divised a new definition for the word element "i mean by element simple unimitagated bodies". -
Late 1700's
Joseph Priesley was the first person to isolate oxygen scientificly. But he did not know that oxygen is an element, this fact was soon rconized by Antoine Lavoisier. -
1800s
However, Daltons atomic model cannot explain why, on a dry winter day, you get a spark when you touch a metal doorknob. obviously, matter is able to develop positive and negitive charges- quanities of electricity that may build up on an object. -
1808
by this time it was generally accepted that matter was made of elements, the two models had come together. English chemist John Dalton published a theory of why elements differ from each other and from non-elements. -
1904
J.J Thomson revised the atomic model further, to explain his discovery of very light negative particles, called electrons. He also did experiments with beams of much heavier positive particles (later identified as protons). -
1911
Ernest Rutherfield, working at Mcgill University in Montreal, designed an experiment to test thompson's and Nagaoka's models. He aimed a type of radiation called alpha particles (positivly charged particles smaller then Atoms). -
Elements
A greek scholar called Empedocles proposed that matter was made of four "elements", Fire,water,air and earth. in the picture which is shown. Thoughs elements mixed together in different sizes to yeild substances.
