Friday, April 15, 2011

Atomic Theory

Greek philosophers believed that atomos that were the smallest pieces of matter.
- Aristotle who believed in four element of earth, air, fire and water
- Alchemist who desired to turn common metals into gold
Their activities marked the beginning of our understanding of matter

But it is not a scientific theory because it could be tested through  observation.

There are a Earliest theory about atomic theory who is Democritus, a 300 b.c. greek philosopher who said that atoms are invisible particles.
Later in the late 1700s came Lavoisier after Democritus, he stated the first version of the law of conservation of mass and Law of difineite proportions
After that, Proust in 1799 proved that Lavoisier's Laws by experiments.
Follow up is Dalton in early 1800s who defined atoms as solid and indestructible spheres base on the Law of Conservation of Mass

Later, J.J. Thomson (1850s)  rose the first theory that have positive and negative charges in atoms and demonstrated the existance of electrons using a cathrode ray tube.
Rutherford in 1905 shwoed atoms have a positve, dense center with electrons outside it and ecplains why electrons spin around nucleus and suggested atoms are mostly empty space.

Atomic Theory IV
Neils Bohr (1885-1962), studied gaseous smaple of atoms, which were made to glow by passin gan electronic current through them.

That's about all of the history of chemists in the earlier eras. These are the ones of the greatest chemists in human history. We learn new things from them. Even the scientists today apply these theories into their experiement and exploration of chemistry. So it is worthwhile to learn about them. I hope you have learned something from this particular blog.

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