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400 BCE
Democritus starts a theory
Democritus first proposed the idea that all objects if cut down small enough you get a small indestructible unit called an atoms. ie: iron would be made of iron particles, clay would have clay particles, etc. -
Period: 400 BCE to
Atomic theory timeline
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Issac Newton
Issac Newton theorized that we lived in a mechanical universe with small solid masses moving in motion.He was one of the first to say that the particles that make up our universe weren't stationary but in constant motion. -
John Dalton
John Dalton Proposed that each object had a unique atom and compounds were the combination of these atoms. This is to sya he though all matter was made up of smaller versions of itself. -
Michael Faraday
developed the two laws of electrochemistry. This broadened our understanding of chemistry and helped get us where we are. -
Jay plucker
Developed one of the first cathode-rays tubes, which is a tube that can shoot out a stream of electrons with a high vacuum tube. This later helped to identify parts of the atom. -
Dmitri Mendeleev
Mendeleev was the first to make and try to fill the periodic table of elements. This table has introduced the topic of chemistry to the masses and helped identify new elements and help us understand atoms even more. -
James Maxwell
Proposed the theory of electromagnetism making the connect between the properties of light and waves. -
G.J Stoney
theorized that electricity was comprised of negative particles he called electrons.This changed the game up forever. -
Sr William Crookes
experiments with cathode-ray tubes led him to confirm the work of earlier scientists by definitively demonstrating that cathode-rays have a negative charge. -
Henry Becquerel
discovered radiation by studying the effects of x-rays on photographic film. -
J.J Thompson
Determined the mass to charge ratio of electrons -
Rutherford
Through studying subatomic particles he estimated that the majority of the weight of an atom was based in the center -
Max planck
Max Planck first introduced the idea of quantization to explain how light was emitted from an object that was so hot it glowed. -
Frederick Soddy
Came up with the term "Isotope" to explain the breakdown of radioactive material -
Hantoro Nagoka
proposed an atomic model called the Saturnian Model to describe the structure of an atom. -
Richard Abegg
Discovered that noble gasses have a stable electron configuration -
Hans Geiger
Invented the Geiger counter, a device used to detect different types of radiation including alpha particles -
Albert Einstein
Mathematically proved the existence of atoms and also published the Special Theory of Relativity which put him on his way to the title of "the father of modern physics". -
Ernest Rutherford
By shooting alpha particles at a thin piece of gold foil he established that the nucleus was very dense and positively charged.He also found out that electrons would have to be around the nucleas. -
H.G.J Mosley
discovered that protons determined atomic number and therefore determined the element -
Francis William Aston
Used a spectograph to identify 212 isotopes -
Niels Bohr
developed the bohr model which is the model most schools teach. This model suggests that the outer rings of an atom could hold more than the innner (2-8-8) -
De Brogliie
discovered that electrons had characteristics similar to both waves and particles -
Werner Heisenberg
suggested the principle of indeterminacy,which states you cannot 100% know a particles speed or location at any point in time -
Erwin Schrodinger
viewed electrons as continuous clouds and brought in a concept called "wave mechanics" as a mathematical model of an atom.combined with Heisenberg's principle of indeterminacy this makes up modern quantum mechanics which is said to be how an atom works.
