Atomic time

The Alchemists

500 BCE

Discovered a substance that would transmute the more common metals into silver and gold. later on they were unsuccessful in turning common items into gold but they did create a scientific process that would allow for the discovery of the atom.

Democritus

400 BCE

Democritus theorized that all material bodies are made up of indivisibly small atoms. He realized that the atom is indeed divisible and that it is not hard, solid, or immutable

Plato

360 BCE

Plato found that according to which atoms broke down mathematically into triangles. This was known as the platonic solids or the philosopher known best as a disciple of socrates.

Solar System Model

330 BCE

The solar system model could illustrate the relative positions and motions of the planets and moons in the solar system.

Robert Boyle

1640

Robert Boyle mainly studied gases but he also discussed the possibility of atoms existing. Boyle believed that all substances were made up of atoms.

Antone Lavoisier

1780

Antone Lavoisier found that mass is conserved in a chemical reaction. His results led to the fundamental laws of chemical behavior and the law of conservation of matter. We now understand that atoms are neither created nor destroyed in a chemical reaction.

Billiard Ball Model

1800

Because Dalton thought atoms were the smallest particles of matter, he envisioned them as solid, hard spheres, like billiard balls. So he used wooden balls to model them.

John Dalton

1803

John Dalton proposed that compounds were atoms from different elements combined together and consisted of atoms that were identical and also had the same mass. He thought that atoms of different elements could be universally distinguished based on varying atomic weights.

Amadeo Avagadro

1811

Amadeo Avagadri is best known for the hypothesis that equal volume of different gasses contain an equal number of molecules.

Dmitri Mendeleev

1869

Mendeleev played a major role in transforming chemistry in Russia. in 1869, Dmitri jotted down the symbols for the chemical elements, putting them in order according to their atomic weights and inventing the periodic table.

JJ Thompson

1897

Sir Joseph John Thompson was an English physicist. Thomson discovered that the atom consist of smaller sub particles called electrons.

Pierre and Marie Curie

1898

French physicists Pierre and Marie Curie discovered the strongly radioactive elements polonium and radium. This showed that the atom was neither invisible nor immutable. The atom could change form and emit energy.

Plum Pudding Model

1904

The plum pudding model has electrons surrounded by a volume of positive charge.

Albert Einstein

1905

Albert Einstein talked about the movements of tiny particles in liquid or gas. This effect was renown as Brownian motion and Einsteins paper regarding it confirmed the atomic theory of matter. This shows that atoms actually exist.

Robert Millikan

1910

Robert Millikan succeeded in determining the magnitude of the electrons charge. He showed that their change always was a multiple of a precisely determined charge, the electron's charge.

Ernest Rutherford

1911

Ernest Rutherford was known to be the father of nuclear physics. He found that the atom consist mostly of empty space, with it'd mass concentrated in a central positively charged nucleus.

Neils Bohr

1912

Neils Bohr had established experimentally that the atom consists of heavy positively charged nucleus with much lighter negatively charged electrons circling around it at considerable distance.

Henry G. J. Moseley

1913

Henry Moseley was an English physicist who created Moseley's law. Mosley's law is characterized concerning x-rays that are produced by atoms. He stated that the frequencies are equal to the squares of whole of whole numbers that are equal to the atomic number added with a constant.

Electron Cloud Model

1926

The electron cloud model knows exactly where an electron is at given time

Erwin Schrodinger

1926

Schrodinger formulated a ware equation that accurately calculated the energy levels of electrons in atoms. Erwin also won the Nobel prize in 1933 for his work on the Schrodinger equation.

Werner Heisenberg

1927

Werner Heisenberg contributed to the atomic theory through formulating quantum mechanic in terms of matrices and in discovering the uncertainty, principle, which states that a particles position and momentum cannot with be known exactly.

James Chadwick

1932

Chadwick made a fundamental discovery in the domain of nuclear science. James Chadwick proved the existence of neutrons which is a basic principle of any electrical charge. James Chadwick was also one of the greatest scientist alive during WW1.