Ideas about Atomsby

Erdem ULUÇINAR

How our ideas about atomic structure have changed over the last 2500 years

A Brief Summary First idea of atom is

seen in Ancient India, Jain and Hindu Philosophers in the sixth century. After sixth century more scientists tought about atom.

IMPORTANT SCIENTISTS WHO WORKED ABOUT ATOM

Democritus

400 B.C. -Democritus thought matter could not be divided indefinitely.

This led to the idea of atoms in a void.

John Dalton

Dalton is the father of the modern atom thought.

He said that: Atoms are all same There are atoms in all matters. In each matter there are different atoms Atoms of different elements combine in

constant ratios to form compounds.

J. J. Thompson

He was born in 1856 and died in 1940 In 1897 he found out electrons in atoms.

That was a milestone for physics. He worked about electricity in his all life

Plum-Pudding WayHe discovered the plum-pudding model of atom in 1904 before the discovery of the atomic nucleus.In "Plum Pudding Model" each atom was a sphere filled with a positively charged fluid. The fluid was called the "pudding." Scattered in this fluid were electrons known as the "plums."

Einstein

In 1827 a Scottish biologist called Robert Brown was working on pollen grains.

To his surprise he saw that pollens were moving randomly. He thought that pollens were alive, so they can move by

their own. But in 1905 Albert Einstein proved that actually pollens

weren’t alive or moving by their own. He proved in water there are small molecules and atoms

which move and crush to pollen so that they move randomly.

Brownian Motion

Ernest Rutherford In Thomson’s atom model

atom had a sphere shape and there were just electrons and protons in an atom. Also people didn’t know wheter they had a pattern.

But in Ernest Rutherford’s atom model there are also neutrons which is different from Thomson’s.

Also he said electrons are in an orbit around atom.

Alpha-particle scattering Rutherford's alpha

scattering experiments were the first experiments in which individual particles were systematically scattered and detected. This is now the standard operating procedure of particle physics. To minimize alpha loss by scattering from air molecules, the experiment was carried out in a fairly good vacuum

James Chadwick

Chadwick found neutrons Chadwick proved Rutherford’s idea about

neutrons He saw there were some particals which

comes out in Rutherford’s experiment. While other scientists were thinking that

was a radiational thing he proved that was a unknown particle came out.

He named that particle as neutron because of its charge

Today’s Atom Model

Chadwick

Rutherford

Einstein

Quarks

Quark is found by Murray Gell-Mann and George Zweig in 1964

A quark is an elementary particle and a fundamental constiduent of matter

Quarks have various intrinsic properties, including electric charge, color charge, spin, and mass.

Prepared By:Erdem ULUÇINAR

ReferencesChemistry-the booken.wikipedia.orgwww2.slac.stanford.eduAip.org