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Period: 500 BCE to
History of the Atom
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400 BCE
Democritus
Theorized some properties of atoms. He also theorized that atoms were specific to the material they composed. Source: American Board -
100 BCE
The Alchemists
Their studies of the scientific process and natural processes allowed us to later discover the atom. Source: Health Research Funding -
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Robert Boyle
Demonstrated that matter is made of tiny particles. He called them corpuscles. Source: Study.com -
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Billiard Ball Model
A model by John Dalton that showed the atom as a ball like structure. Source: Brilliant -
John Dalton
Published a theory on atomic theory. He suggested that all matter is made of atoms with distinct properties (elements). Source: Royal Society -
Amedeo Avogadro
Stated that equal volumes of gases at the same temperature contained the same number of molecules. He also stated that elementary gases are composed of two atoms. Source: Le Monye College -
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J.J. Thomson
Came up with an experiment that proved the existence of electrons. Source: Khan Academy -
Pierre and Marie Curie
Discovered and coined the term radioactivity by discovering radium and polodium. Source: Britannica -
Plum Pudding Model
A model by J.J. Thomson that had electrons embedded in a positively-charged soup. Source: Khan Academy -
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Ernest Rutherford
Established that the mass of an atom is concentrated in its nucleus. Source: Primary Connections -
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Henry G. J. Mosely
Arranged the elements of the periodic table by atomic number and proved that the atomic number is the number of positive charges in the atomic nucleus. Source: Britannica -
Solar System Model
A model by Neils Borh that showed that electrons orbit the nucleus. Source: American Board -
Electron Cloud Model
A model used to estimate the location of electrons. It was developed by Erwin Schrödinger and Werner Heisenberg. Source: Study.com -
