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427 BCE
Plato
Plato introduced the atomic theory. In which the ideal geometric forms serve as atoms, according to which atoms broke down mathematically into triangles. -
400 BCE
Democritus
Everything is made of atoms, which are physically indivisible. The atoms are indestructible and always have been and always will be in motion. That there is an infinite number of atoms and kinds of atoms. -
330 BCE
Solar system model
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332
Aristotle
He believed that everything was a combination of four elements: air, water, fire, and earth. -
The Alchemists
There practitioners mainly sought to turn lead to gold. They believed there were four basic elements: air, water, fire, and earth. One of the most famous Alchemists was Isaac Newton. -
Robert Boyle
He discovered that the volume of gas decreases with increasing pressure and vice versa. Which this is called the Boyle's law. -
lavoisier
Though a series of experiments he found that the total mass of products and reactants in a chemical reactions is always the same. This led to the theory of the law of conservation mass. -
John Dalton
John Dalton is best known for the Atomism. He said that all matter was made of atoms, indivisible, and indestructible building blocks. -
solid sphere of billiard ball model
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Dmitri Mendeleev
He develop the periodic classification of the elements. He found that all known chemical elements were arranged in order of increasing atomic weight or periodicity. -
J.J. Thomson
His experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. -
plum pudding model
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The curies
The rays, she theorized, came from elements atomic structure. This revolutionary idea created the field of atomic structures. -
Albert Einstein
He is known for the theory of relativity. It means that it is a theory of gravity. Its the basic idea that instead of being an invisible force that attracts objects to one another, gravity is curving or warping space. -
Robert Millikan
His oil drop experiment helped to quantify the charge of an electron. This greatly contributed to our understanding of the atom and atomic theory. -
Ernest Rutherford
Rutherford postulated the nuclear structure of the atom. Discovered alpha and beta rays, and proposed the laws of radioactive decay. -
Niels Bohr
He proposed a theory that hydrogen atom based quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. -
Henry G.J. Mosely
He used self-built equipment to prove that every element's identity is uniquely determined by how many protons it has. This helped him predict 4 new chemical elements, all of which were found. -
Electron Cloud Model
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Werner Heisenberg
He formulated a quantum mechanics in terms of matrices and in discovering the uncertainty principle, which states tat a particle's position and momentum cannot both be know exactly
