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Democritus came up with the concept of atoms. -
Plato developed the idea of an element. he also theorized that these solids forms of matter are composed of indivisible elements shaped like triangles. -
The Solar System Model is the placing of planets in order from the Earth. -
The Alchemists laid out the groundwork for chemical process. Some examples are leather tanning, manufacture of glass, production of gunpowder, and production of inks, paints and dyes. -
Robert Boyle discovered that the volume of a gas decreases with increasing pressure and vice versa. -
Amedeo Avogadro had 2 hypotheses. number 1 being, that equal volumes of gas contain equal numbers of molecules. number 2 was, that elementary gases, such as hydrogen, nitrogen, and oxygen were composed of two atoms. -
Antone Lavoisier established the law of conservation of mass. He also made the first attempt to organize the elements of the periodic table based on the classification of their chemical properties. -
John Dalton created the atomic theory. "all matter was comprised of indivisible and indestructible atoms with distinct masses and properties, the combination of which determined the physical nature of their constant elements. -
The Billiard ball Model also known as Daltons Model of an Atom. He defined an atom to be a ball like structure, as the concepts of atomic nucleus and elements were unknown at the time. -
Robert Millikan discovered the elementary charge of an electron using the oil-drop experiment. -
Dmitri Mendeleev devised the periodic table. -
Ernest Rutherford found out that atoms have a nucleus. -
JJ Thompson discovered the electron and went on to propose a model for the structure of the atom. -
The Plum Pudding Model are negatively charged electrons embedded within a positively charged "soup" -
Albert Einstein mathematically predicted the size of both atoms and molecules. he also proved atoms existed. -
Neils Bohr proposed a theory for the hydrogen atom. -
Henry G. J. Mosely arranged the elements in the periodic table according to atomic numbers. -
The Electron Cloud Model represents the area around an atoms nucleus where electrons are most likely to be found. -
Pierre and Marie Curie made the discovery of a new element 400 times more radioactive that uranium. -
James Chadwick proved the existence of neutrons.