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200
440 BCE - Democritus
a greek philosopher named a particle called the atom. The word atom, is fro a Greek atomos meaning " Not able to divide". He said that they were small, hard particles made up of a single material formed into different shapes and sizes. -
201
440 BCE- Aristotle
Aristotle was a greek philosopher. He disagreed with Democritus's ideas. He thought that you could not ever end up with a particle that could not be cut. -
Dalton
Dalton was a British Chemist and schoolteacher. He experimented with different substances and his result seggusted that the elements conbined in a certian proportion are made up of atoms. -
Thomson
J.J. Thomson had proved that Dalton was wrong. Thomson had discovered that their are small particle inside the atoms. Because of this, atoms can be divided into smaller parts. -
Rutherford 1909
rutherford decided to test Thomsons therory. He aimed a small, positivley charged particles of a thin sheet of gold foil. He put a special coating behind the gold foil. the special coating glowed when the light hit it. When it was hit, rutherford could see where the particles went after hitting the gold. -
Rutherford 1911
In 1911, Rutherford had decided to revise the atomic therory. He made a new model of the atom. While revising the atomic therory, he discovered something inside the atom called a nucleus. A nucleus is tiny, extremely dense, and positivley charged -
Bohr
Niels Bohr was a Danish scientish who had workedm wirth Rutherford on the way atooms react with light. The result led him to propose that there are electrons that move around the nucleus in a certian paths, or energy levels. But in Bohrs model there are no paths between the levels . but also, electrons can jump from a path in one level to another path on another level. -
Schrodinger and Heisenberg
A Australian physicist named Erwin Schrodinger and a Germen physicist named Werner Heisenberg had further explained the nature of electrons in a atom. The had found out that Bohr was wrong and that the exact path of an electron cannot be perdicted. -
Period: to
440 BCE - Democritus
