Atomic Theory Project 2022

Democritus

370 BCE

Democritus was a Greek philosopher born in 460 B.C in Thrace. He is the earliest person to ever propose the theory of atoms. His theory states that atoms are invisible, invincible objects. He claims that atoms are infinite and constantly moving throughout the world and always have been (Berryman, 2004). Interestingly, none of Democritus's work has survived and he died in 370 B.C

Painting of Democritus

370 BCE

John Dalton's Atomic Theory

1808

John Dalton was a British chemist and physicist who was born on 9/6/1766 and died on 7/27/1844 at the age of 77. John Dalton in 1808 proposed his own atomic theory, which was similar to Democritus's. His theory states that atoms are small particles that make up all matter and are invisible and invincible (BYJU's, 2020). John Dalton was actually the first ever scientist to use the actual word 'atom' (World History Edu., 2021).

John Dalton Portrait

1808

JJ Thomson's Electron Discovery

1897

Joseph John Thomson was a British physicist born on December 18, 1856, in Manchester, U.K, Joseph John Thomson, or J.J Thomson, is credited with discovering the electron. Thomson discovered the electron while conducting an experiment with cathode rays. Thomson then proposed his very own atom model, based on his observations and discovery of subatomic particles. J.J Thomson received the Nobel Prize for Physics in 1906. J.J Thomson died on August 30, 1940 (Nobel Prize Outreach, 2022a).

JJ Thomson Picture

1897

Ernest Rutherford's Atomic Nucleus Theory

1911

Ernest, Baron Rutherford of Nelson was born on August 30, 1871, in New Zealand. Ernest Rutherford became an established physicist and in 1911, Ernest Rutherford came up with the Atomic Nucleus Theory. Rutherford theorizes that an atom is mostly empty with the concentration of its mass being located in the center of the atom. He also theorized that electrons orbit the atom a distance away from the center (Badash, 2022).

Ernest Rutherford Picture

1911

Robert Millikan's Electron Revelations

1913

Robert Andrews Millikan was an American physicist born on March 22, 1868, in Illinois. Robert Millikan's atomic discovery was how to properly determine the charge of an atom. Using his "falling-drop" method, Millikan was able to get an accurate charge of an electron. In 1923, Millikan won the Nobel Prize in Physics. And on December 19, 1953, Robert Millikan died in California (Nobel Prize Outreach 2022b).

Nies Bohr's Quantum Theory

1913

Niels Hendrick David Bohr was a Danish physicist born on October 7, 1885, in Copenhagen Denmark. In 1913, Neils Bohr proposed his Quantum Theory. Bohr's theory states that electrons orbit the nucleus, but only in precise patterns. His theory also states that when an electron jumps an orbit level, radiation/energy is released (Nobel Prize Outreach, 2022c). Bohr won the Nobel Prize in Physics in 1922, and died in Copenhagen on November 18, 1962.

Robert Millikan Photo

1913

Niels Bohr Photo

1913

Werner Heisenberg's Uncertainty Principle

1927

Werner Karl Heisenberg is a German physicist born on December 5, 1901; he also won the Nobel Prize for Physics in 1932 and died February 1st, 1976, in West Germany (Nobel Prize Outreach, 2022d). Werner Heisenberg is most known for his revolutionary "Uncertainty Principle". His theory states " that we cannot know both the position and speed of a particle, the more we nail down the particle's position, the less we know about its speed and vice versa." (California Institute of Technology, 2022)

Erwin Schrodinger's Corrections

1927

1933 Nobel Prize in Physics winner, Erwin R.J.A Schrodinger was an Austrian physicist born on August 12, 1887, in Vienna, Austria. Schrodinger's contribution to atomic theory was revisions on Niels Bohr's very own atomic theory made in 1913. Schrodinger theorizes that the quantization of an atom can be determined using an equation that shares the same name as the physicist. Using the Schrodinger Equation, you can determine how the wave function of an atom's electron evolves (Bernstein, 2022).

Werner Heisenberg Photo

1927

Erwin Schrodinger photo

1927

James Chadwick's Discovery of the Neutron

1932

James Chadwick was a British Physicist born on October 20, 1891, in Bollington, England. In 1932, Chadwick discovered a new subatomic particle, the neutron. Chadwick's discovery was revolutionary to the atomic theory, and for this he won the Nobel Prize in Physics in 1935. James Chadwick died on July 24, 1974. (Comunale 2021)

James Chadwick Photo

1932