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450 BCE
Democritus
He was the first person to theorize that all material bodies are made up of indivisibly small atoms in 450 BCE. The famous Aristotle rejected his theory even though it ended up being correct. -
420 BCE
Plato
He was convinced that atoms of matter must derive from 5 fundamental solids in 420 BC. Platos cosmology derives from a mathematical discover -
Robert Boyle
He helped develop a definition of an element in 1662. He also made Boyles Law about gases -
Antone Lavosier
He found that the total mass of products and reactants in a chemical reaction is always the same and he discovered this in 1764. He was known as the father of modern chemistry -
The Alchemists
They presented the atomic theory in the multivolume new system of chemical philosophy in 1803. They're most familiar quest was to find the philosopher's stone. -
John Dalton
He had the first complete attempt to describe all matter in terms of atoms and their properties in 1808. He had 3 parts to his theory -
Billiard Ball Model
The billiard ball model was created by John Dalton in 1808 -
Amadeo Avagadro
Made the hypothesis that equal volumes of different gases contain an equal number of molecules in 1811. His hypothesis only gained acceptance after he died -
Dmitri Mendeleev
He devised the periodic classification of the chemical element 1869. He arranged it in order of increasing atomic weight -
Plum Pudding Model
The plum pudding model was made in 1897 by JJ Thompson -
Pierre and Marie Curie
Discovered the strongly radioactive elements polonium and radium in 1898. They were most known for their studies of radioactivity -
Ernest Rutherford
He was known for his pioneering studies of radioactivity and the atom in 1900. He discovered 2 types of radiation alpha and beta particles -
JJ Thompson
He showed that all atoms contain tiny negatively charged subatomic particles or electrons and he discovered this in 1904. He made the plum pudding model to prove this theory. -
Albert Einstein
In 1905 he mathematically proved the existence of atoms. When Einstein was young he wasn't as observant as he was -
Robert Millikan
Ge discovered the value for electron charge through a oil drop experiment in 1910. He spent the majority of his career as a professor -
Neils Bohr
He proposed the theory that stated that for a hydrogen atom based on quantum theory that some physical quantities only take discrete values and he proposed this in 1913. He also made the first atomic model to use the quantum theory -
Solar System Model
The solar system model was created by Niels Bohr in 193 -
Henry G.J Moseley
He concluded that the atomic number is the number of positive charges in the atomic nucleus in 1914. He made Moseley's Law for atoms -
Erwin Schrodinger
He used the mathematical equations to describe the likelihood of finding an electron in a certain position in 1926. His model was known as the quantum mechanical model. -
Electron Cloud Model
Shrodinger made the electron cloud model in 1926 -
Erner Heisinburg
He formulated quantum mechanics in terms of matrices in 1927. Schrodingers ideas led to Heisinburgs discovery -
James Chadwick
He discovered the neutron in 1932. He discovered that it has the same mass of a proton