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400
Democritus
He state that the universe is composed of two elements: the atoms and the void in which they exist and move. he think that atoms cannot be destroyed, are always moving, and are indovisible. -
400
Aristotle
He did not believe in the atomic theory and thought that all materials on earth is made up of the four elements, earth, air, fire, and water. Most people folloe Aristotle because he is more famous but they prove him incorrect about 2,000 years later. -
Robert Boyle
He proposed that elements are composed of corpuscles of various types and sizes that are able to organize themselves into groups that represent different chemical substances. -
Isaac Newton
he proposed a mechanical universe with small solid masses in motion. which means that there were little tiny pieces of mass that were 'swimming' everywhere. -
Antoine Lavoiser
he turn HgO into Hg+O and used this experiment to come up with the Law of Conservation it states that matter cannot be made or destroyed. Matter can rearranged, but never disappeared. -
Joseph Proust
he tated the Law of Definite Proportions which mean the ratio of elents is always the same or constant. -
John Dalton
He revied the Democritus atomic theory. -
Amedeo Avogadro
said that all of those small tiny elements when they interact with other elements they get to make up a propotions. atoma into a moecule.
-it takes millions and millions of molecule to make a drop of water. -
Michael Faraday
Studied the effect of electricity on solutions, coined term "electrolysis" as a splitting of molecules with electricity and developed laws of electrolysis. -
Dimiti Mendeleev
HE formulated the periodic law and created hiw own version of periodic table. -
Henri Becquerel
he discovered radium activity. -
Marie and Pierre Curie
they dicover radioactive elements polonium and radium. -
Joseph J. Thompson
He discovered electron and changed the whole view of atoms. That atoms caontained small negative charged particles. he thought these electrons were evenly embedded throughout a positiviley charged phere and notice that atoms can be divided -
Albert Einstein
he proved the existence of atom by using E=mc 2. -
Ernest Rutherford
He proposed that all mass of an atom and all it's positive charges were concentrated in a central atomic nucleus surrounded by electrons. Atom is amolst epmty space. -
James Chadwick
concluded that the nucleus contained positive protons and neutral neutrons. -
Niel Bohr
Propse that electorn's orbit the nucleus without losing energy;
could move only in fixed orbits of specific energies. -
Frederick Soddy
he observed spontaneous disintegration of radioactive elements into variants he called isotopes and discovered "half-life", made initial calculations on energy released during decay. -
electron cloud of prabablity
Accoriding to the current accepted model of atomic structure, electrons don't follow fixed orbits but tend to occur more frequently in certain areas around the nucleus at any given time.
