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460
Democritus BC
Grouping of atoms make up diiferent thing in the world : atoms have the same size, weight, mass and shape. he believed that everything in the world is made up of tiny , invisible parts. -
Dalton
All matter composed of atoms. All atoms of an element were identical , defferent elements had atoms of diferent sizes and mass. Theriosed that chemical element atoms have a unique atomis weight and can be placed in order on what is known today as the peridic table . -
Thomson
atoms did indeed contaibn particles known as electrons. He discovered this through finding that cathode raus could be deflected by an electric fiekld , thus concluding that these rays were composed of very light negatively charged particles which he called corpuscles. This proved Stoney's hypothesis and thus other consequences was correct. -
Rutherford
Discovered the basic form of an atom regarding protons and electrons. matter is neutral; some postive charge must balance the charge of the electron. Nicknamed the plum pudding model. -
Bohr
He suggested that when an atom is excited or heated , electrons can jump to higher levels, and when the atom cools, they drop down to where precise quanta of energy is released as specifi wavelenghts. Developed an explanation of atomis structure that agrees with the periodic table . -
Heisenberg and Schrodinger
No experiment can measure the postion of a particle, uncertainly in the monentum gets layer. Cannot measure the position and momeritum of aquafntum particle simultenecudla. "Heisenbery once Aainty principle" -
Aristotle BC
He thought all materials on Earth were not made of atoms, but of wind,Earth , water ,and air .He thought that substances were made of small amounts of these four elements. He developed the scientic method .