History Of The Atom

Front 1

Philosophy

Back 1

way of thinking, no experiments

Front 2

Democritus

Back 2

Matter is made of atoms, small spheres, just thought about it

Front 3

Aristotle

Back 3

Matter was continuous and made of ether, overshadowed Democritus' ideas

Front 4

Antoine Lavoisier

Back 4

performed experiments involving chemical reactions, starting mass is same as ending mass

Front 5

Law of Conservation of Matter

Back 5

Matter cannot be created nor destroyed in a chemical reaction

Front 6

Joseph Proust

Back 6

preformed experiments involving chemical reactions, amount of starting material always reacted in the same ratios

Front 7

Law of Definite Proportions

Back 7

elements that comprise a compound are always in a certain proportion

Front 8

John Dalton

Back 8

English school teacher, proposed the first true atomic theory

Front 9

Dalton's Atomic Theory

Back 9

Matter is composed of atoms, Atoms are indivisible and indestructible, Atoms of the same element are the same, Atoms of different elements are different, Atoms combine in whole number ratios, In chemical reaction atoms are rearranged, combined, or seperated. Not fully correct, does not explain everything.

Front 10

Eugene Goldstein

Back 10

Observed anode rays, Atoms have posetively charged particles called protons

Front 11

J.J. Thomson

Back 11

atoms contain electrons, used cathode ray tube, beam of light, magnet, plum pudding model

Front 12

Robert Milikan

Back 12

discovered charge and mass of electron

Front 13

James Chadwick

Back 13

discovered neutron, different masses of same element, mass was due to new particle (neutron)

Front 14

Ernest Rutherford

Back 14

experiments that showed most of atom is empty space, most of mass is located in the center, nucleus

Front 15

Rutherford's experiment

Back 15

shot particles at sheet of gold foil, some particles deflected, some straight through, atom is mostly empty space