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460 BCE
Early Greek Models - Democritus
Democritus was born in Abdera, Greece in 460BC. He studied natural philosophy. His mentor, Leucippus, originally came up with the atomic theory, but it was then adopted by Democritus. According to Democritus atoms were miniscule quantities of matter. Democritus hypothesized that atoms cannot be destroyed, differ in size, shape and temperature, are always moving, and are invisible. He believed that there are an infinite number of atoms. He lived to be 90 years old, dying in the year 370BC -
Feb 11, 1144
Medieval Alchemy
Medieval alchemy was the idea that all matter was composed of four elements: earth, air, fire and water. With the right combination of elements, it was theorized; any substance on earth might be formed. This included precious metals as well as elixirs to cure disease and prolong life. Alchemy is also the name of the Gnostic philosophy that undergirded the alchemical activity, a practical philosophy of spiritual purification. The introduction to Latin Europe may be dated to 11 February 1144. -
John Dalton
Was best known for his pioneering work in the development of modern atomic theory, along with his research into colourblindness (also sometimes referred as Daltonism). Dalton's work led him to conclude that chemical combinations happen between particles of different atomic weights, a groundbreaking concept that outshone the assumptions of many of the Ancient Greeks. He had a rare form of colourblindness (only able to see yellow). Died on July 27, 1844 (at age 77) after suffering a second stroke. -
Henri Becquerel
Henri Becquerel born into a family of scientists, Becquerel followed his father into the academic field of physics. Henri was a French physicist, Nobel laureate, and the first person to discover evidence of radioactivity. For work in this field he, along with Marie Skłodowska-Curie and Pierre Curie, received the 1903 Nobel Prize in Physics. The SI unit for radioactivity, the Becquerel (Bq), is named after him. Died on August 25, 1908 (at age 55). -
J. J. Thomson
English physicist who helped revolutionize the knowledge of atomic structure by his discovery of the electron. He also found the first evidence that stable elements can exist as isotopes and invented one of the most powerful tools in analytical chemistry (the mass spectrometer). Aston went on to win the 1922 Nobel Prize in Chemistry for continuing this work, discovering that all isotope masses were whole number multiples of the hydrogen atom’s mass. Died on August 30, 1940 (at age 83). -
Ernest Rutherford
A pioneer of nuclear physics and the first to split the atom, Rutherford was awarded the 1908 Nobel Prize in Chemistry for his theory of atomic structure. He died in Cambridge on October 19, 1937 (at age 66). Rutherford performed his most famous work after receiving the Nobel Prize in 1908. Along with Hans Geiger and Ernest Marsden in 1909, he carried out the Geiger–Marsden experiment, which demonstrated the nuclear nature of atoms by deflecting alpha particles passing through a thin gold foil. -
Neils Bohr
Neils Bohr was a physicist and humanitarian whose revolutionary theories on atomic structures helped shape research worldwide along with, foundational contributions to understanding atomic structure and quantum theory. He won the 1922 Nobel Prize in physics for his ideas and years later, after working on the Manhattan Project in the United States, called for responsible and peaceful applications of atomic energy across the world. Died on November 18,1962(at age 77) from Congestive heart failure. -
James Chadwick
James Chadwick was English physicist who was awarded the 1935 Nobel Prize in Physics. He played a vital role in the atomic theory as he discovered the Neutron in atoms in 1932. Chadwick graduated from the Victoria University of Manchester in 1911, where he studied under Ernest Rutherford. He led the British team in the Manhattan Project, in which the UK and Canada supported the USA’s World War 2 effort to build the world’s first nuclear bomb. He died on July 24, 1974 (at age 82). -
Marie and Pierre Curie
Pierre and Marie Curie (married in 1895) are best known for their pioneering work in the study of radioactivity, which led to their discovery in 1898 of the elements radium and polonium. The Curies won a Nobel Prize for Physics in 1903.Their work, which by its nature dealt with changes in the atomic nucleus, led the way toward the modern understanding of the atom as an entity that can be split to release enormous energy. Marie died on July 4, 1934(age 66), Pierre died on April 19, 1906 (age 46).
