Atomic Model

The Alchemist

500 BCE

The goal of the alchemists was to transmute common elements (like lead) into gold. The alchemists believed that there were seven "base elements."

Democritus

442 BCE

Democritus’s model stated that matter consists of invisible particles called atoms and a void

Plato

400 BCE

Plato introduced the atomic theory in which ideal geometric forms serve as atoms, according to which atoms broke down mathematically into triangles, such that the form elements had the following shape: fire (tetrahedron), air (octahedron), water (icosahedron), earth (cube).

Aristotle

332 BCE

Aristotle believed that it was possible to determine which substances contained more or less of each element based on its structure, design, and composition.

Robert Boyle

1650

Robert Boyle is known as “The Father of Chemistry” for his discovery that atoms must exist based on the relationship between pressure and volume of gas.

Lavoisier

1777

The modern Atomic Model was first developed by two key scientists Lavoisier and Dalton with the help of others. They formulated the key concepts of the law of conservation of mass and the existence of atoms as the building blocks of all matter using their knowledge of chemical reactions.

John Dalton

1808

Dalton’s atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks.

Dmitri Mendeleev

1869

He put forward a hypothesis that there existed two inert chemical elements of lesser atomic weight than hydrogen.

J.J. Thomson

1900

Thomson atomic model, was the earliest theoretical description of the inner structure of atoms,

The Curies

1902

Pierre and Marie Curie were to discover and isolate radium, a new element which spontaneously disintegrated into other elements.

Albert Einstein

1905

He was able to fully prove through usage of evidence that atoms did indeed exist, and he was also able to demonstrate that electrons could leave metal through usage of light. He also created the mass energy equivalence equation, and this paved the way for the creation of the atomic bomb.

Robert Millikan

1909

He thought that cosmic ray photons were the "birth cries" of new atoms continually being created by God to interact entropy and prevent heat death. he also determined the unit charge of the electron in 1909 with his oil drop experiment at the University of Chicago.

Ernest Rutherford

1911

Rutherford envisioned the atom as a miniature solar system, with electrons orbiting around a massive nucleus, and as mostly empty space, with the nucleus occupying only a very small part of the atom.

Henry G. J. Mosely

1912

Proposed that the atom contains in its nucleus a number of positive nuclear charges that is equal to its (atomic) number in the periodic table.

Neils Bohr

1913

Bohr developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another.

Werner Heisenberg

1925

Heisenberg said that the electrons do not move in neat orbits around the nucleus like planets, but in fact all electrons contain photons and then change the momentum and physics of the atom.