Atomic Theory

Atomic Theory

TIMELINE of the DEVELOPEMENT of the ATOMIC THEORY

442 BC

Thinking about atoms

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Pierre and Marie Curie theorized that radioactive particles cause atoms to break down, then releasing radiation that takes the form of energy and subatomic particles.

James Chadwick discovers the neutron component of the atomic nucleus, explaining the nuclear fission of uranium 235.

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1803

John Dalton Atoms

1898

Radiation, energy, and the atom electrons found

1909

1931

Structure of an atom developed

Neutron is discovered

Democritus, a Greek philosopher, co-originated the thought that all matter is composed of indivisible elements.

John Dalton developed a theory that matter is simply composed of atoms of different weights and

Ernest Rutherford known as the father of nuclear physics, developed the theory for the

structure of the atom. He used a gold foil experiment, observing the scattering of alpha

particles, and demonstrated for the first time the existence of the atomic nucleus.

JJ Thomson discovers the electron, using properties of cathode rays

is combined in ratios by weight. Proposed that these atoms are also spherical, and are in motion.