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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 shapes.
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Democritus theorized that all materials bodies are made up of indivisibly small ‘atoms.’
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Aristotle did not believe in the atomic theory and he taught so otherwise. He thought that all materials on Earth were not made of atoms, but of the four elements, Earth, Fire, Water, and Air. He believed all substances were made of small amounts of these four elements of matter.
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Understanding that his results could be explained if all gases were made of tiny particles, Boyle tried to construct a universal ‘corpuscular theory’ of chemistry.
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Alchemy contributed to the atomic theory, by laying down the foundation of the modern-day periodic table of elements
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Lavoisier found that mass is conserved in a chemical reaction. We now understand why matter is conserved -- atoms are neither created nor destroyed in a chemical reaction.
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Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. ... Dalton also postulated that chemical reactions resulted in the rearrangement of the reacting atoms.
• The Solid Sphere model is an atomic model proposed by John Dalton in 1803 stating that all objects are made of particles called atoms -
he created the first Periodic Table. The Periodic Law states that when elements are arranged according to their atomic number, elements with similar properties will appear at regular intervals
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Summary. J.J. Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson proposed the plum pudding model of the atom, which had negatively charged electrons embedded within a positively charged "soup."
• Thomson's “Plum Pudding” Model. In 1897, Joseph John Thomas had announced the discovery of a corpuscle. -
The curies discovered the strongly radioactive elements polonium and radium, which occur naturally in uranium minerals. Marie coined the term radioactive for the spontaneous emission of ionizing, penetrating rays by certain atoms.
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Einstein mathematically proved the existence of atoms, and thus helped revolutionize all the sciences through the use of statistics and probability
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Ernest Rutherford postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay.
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His oil drop experiment helped to quantify the charge of an electron, which contributed greatly to our understanding of the structure of the atom and atomic theory.
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he used self-built equipment to prove that every element's identity is uniquely determined by the number of protons it has. His discovery revealed the true basis of the periodic table and enabled Moseley to predict confidently the existence of four new chemical elements, all of which were found.
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Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well-defined quantities. His theory could explain why toms emitted light in fixed wavelengths
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Werner Heisenberg contributed to atomic theory through formulating quantum mechanics in terms of matrices and in discovering the uncertainty principle, which states that a particle's position and momentum cannot both be known exactly.
