Chemistry History of the Atomic Theory

Only used reasoning, no scientific process

Democritus

All matter is made up of atoms and atoms are indivisible

Democritus

1st to scientifically study the atom

John Dalton

Discovered Dalton’s Atomic Theory

John Dalton

Cathode Ray Tube Experiment

JJ Thomson

Discovered: Atom is a positive sphere w/ negatively charged particles. AND The electron

JJ Thomson

Oil Drop experiment

Robert Millikan

Discovered: determined the charge and the mass of electrons

Robert Millikan

Gold Foil Experiment

Ernest Rutherford

Discovered: The nuclear atom. Atoms are made up of mostly empty space. The nucleus:atoms have small, dense, positive nucleus

Ernest Rutherford

Both of these people didn’t have research

James Chadwick and Eugene Goldstein

Discovered: Neutrons: no net charge

James Chadwick

Discovered: Protons: net positive charge

Eugene Goldstein

True or false about Dalton’s Atomic Theory: All elements are composed of tiny indivisible particles called atoms. Atoms of one element are different from those of any other atom.

False: Used to be true but has been corrected over time

True or false about Dalton’s Atomic Theory: All atoms of the same element are identical

False: Used to be true but has been corrected over time

True or false about Dalton’s Atomic Theory: Atoms are different elements can combine to form compounds in simple who-number ratios

True

True or false about Dalton’s Atomic Theory: Chemical reactions occur when atoms are rearranged. Atoms are never created nor destroyed in a reaction

True