Hoyo-Quersher-Per.1

Democritus

450

-Democritus questioned how many times could you cut something up until it was in its smallest state.
-He thought the atom looked liike a really small circle
-He also came up with the notion of the atom.

Aristotle

460

-thought everything was made up of either earth, wind, fire or water.
-he didnt think there was a smallest part of matter.
-had a different theory than other philosophers.
-some people followed his beliefs.

John Dalton

Oct 24, 1780

-Daltons atomic theory:
1. atoms make up an element
2. atoms of the same element are identical
3. atoms of different elements are different
4. atoms of different elements react to form compounds
5.atoms cannot be created or destroyed, they can only be changed
-he was known as the father of the atomic theory
-he thought the atom was like a pool ball

J.J. Thomson

Oct 24, 1890

-used the cathode ray tube experiment. He found something negative in it. He called this the electron
-Thomson was the first to discover the electron
-He also had the plum pudding model to show where the electrons were in his theory of the atom

Henri Becquerel

Oct 25, 1896

-discovered radioactivity
-his theory was affective, we still use radiation today
-he questioned the direction the rays would travel

Marie and Pierre Curie

Oct 25, 1903

-they studided radioactivity
-thought atoms were radioactive
-discovered radium and polonium
-did experiments on xrays

Robert Millikan

Oct 25, 1910

-created the oil drop experiment
-he also figured out the charge of an electron
-discovered how much a charge on an atom can affect the gravity of the atom

Ernest Rutherford

Oct 24, 1911

-had the gold foil experiment
-there was heavy radiation
-he also created the Rutherord e- cloud model. It had a very small, dense and positive center known as the nucleus (he discovered the nucleus)

Niels Bohr

Oct 25, 1913

-thought the atoms were set up like the planets around the sun
-did experiments on the energy of atoms
-he also contributed to the structure of the atom

Quantum model

Oct 25, 1925

-Erwin Schrodinger created this model
-he used the compton effect to prove it
-his atom includes a nucleus with the protons and neutrons in it just like many other scientists theories did.

James Chadwick

Oct 25, 1932

-discovered the neutron. it had a lack of electric charge
-he was awarded the Nobel Prize for physic in 1935
-he inspired other scientists
-he would do experiments with the alpha particles.