History of the Atom by Jeff and Jara

Aristotle (BCE)

332

-discovered that matter must be broken into smaller pieces.
-a method he used for his dicovery was the Metaphysic book, defining the subject matter, considering the difficulties , involved by reviewing the generally accepted views, presenting his own arguements and solutions.
-used his senses to guess what the atom looks like; the way things really seem to be.

Democritus (BC)

460

-He asked " If you break a piece of matter in half, and the break it half again, how many breaks will you have to make before you cant break it any further?"
-developed the idea of atoms
-believed atoms could not be broken into smaller matter forever
-did not have a method to make his discovery
-thought atoms were invisivble.

Dalton

Jan 1, 1801

-discovered that elements are made of atoms
-said that atoms can not be changed into differnt atoms by chemical reactions.
-also that compounds are formed when putting two atoms together.
-A method he used for his discovery was Dalton's Law of Partial Pressures
-And proposed an "atomic theory" w/ spherical solids atoms based upon measurable properties of mass.

Thomson

Mar 5, 1897

-discovered electons. (knew they were negative charged)
-thought matter had a positve charge.
-A method he used to make his discovery was the "Plum Pudding Theory"

Rutherford

Mar 5, 1911

-Discovered that atoms break into tiny, positive matter
- also that the nucleus was very dense, very small, and positivly charged
-he assumed electrons were located outside the nucleus
-A method he used to make his discovery was bombing atoms with alpha rays

Bohr

Mar 6, 1922

• Developed an explanation of atomic structure that underlies regularities of the periodic table of elements.
• He added to Rutherford's theory.

Heisenberg and Schrodinger

Mar 6, 1932

• allarctic forms of hydrogen and developed a theory of quantam physics. -used a wave of quantam physics make a discovery.