The Atomic Theory

Democritus is born.

440 BCE

440 B.C

Atomic Theory is created,

400 BCE

Democritus
All matter consists of invisible particles called atoms. Atoms are indestructible. Atoms are solid but invisible. Atoms are homogenous. Atoms differ in size, shape, mass, position, and arrangement. Liquids are made of large, round atoms. Oils are made of very fine, small atoms that can easily slip past each other.
Solids are made of small, pointy atoms.

Aristotle is born. The contradicting force.

383 BCE

384 B.C, this is the man that contradicts Democritus's initial statement of atom divisibility.

Aristotle's Countertheory

354 BCE

Aristotle stated that all atoms came from small particles that essentially originated from air, fire, water, and earth, the elements.

John Dalton's Law of Conservation of Mass

Oct 7, 1800

States that mass in an object stays the same amount despite chemical or physical change.

J.J Thompson

Mar 9, 1896

This scientist from 1897, said that atoms have other small divisible particles inside. Also invented the Cathode Ray Tube, which has a plate that attracts negative particles. However, even after proving Dalton's theory wrong, he can't find the positive charge in his model.

Millikan

Jul 1, 1909

An American scientist in 1909, by the name of Millikan, determines what amount of mass is inside an electron, confirms negative charge in electron and found that they are in every atom.

Ernest Rutherford , Thompson's pupil

Aug 6, 1909

Adds a gold plate to JJ's tube to spread positive charge. Identifies the nucleus of the atom and that electrons move and are arranged indefinetly.

Neils Bohr

Nov 5, 1913

Danish scientist discovers orbits on atoms, where electrons float through.

Erwin Schrodinger & Werner Heisenberg

Aug 10, 1933

Electrons do not travel in orbits, they said. Instead, they do so in orbitals and there are clouds of electrons.