paige carroll


Democritus atomic model developed

Approx. 442 BC

Democritus proposed that all matter is composed of indivisible elements.

John Dalton Publishes First Book

Approx. 1793

John Dalton published his frist book, “Meteorological Observations and Essays”. This book explained the foundation of his later dicoveries.

Dalton's Theory

Approx. 1803

John Dalton developed a theory that matter is simply composed of atoms of different weights. He aslo said that that these atoms are spherical and in motion.

Thompson's Discovery


JJ Thompson discovered the electron, using properties of cathode rays.

Ruthford's Theory

1909 - 1911

Ernest Ruthford, father of nuclear physics, developed the theory for the structure of the atom. He used a gold foil experiment and demonstrated for the first time the existence of the atomic nucleus.

Bohr developed model


Neils Bohr developed the Bohr atomic model. It showed that electrons travelling in orbits around the nucleus, and chemical properties being determined by how many electrons are in the outer orbits.

Shrodinger develops equation


Erwin Shrodinger described how electrons move in wave form, and developed the Schrodinger equation which describes how the quantum state of a system changes with time.

Chadwick's Discovery


James Chadwick discovered the neutron component of the atomic nucleus. This also made it possible to produce elements heavier than uranium in the lab.