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John Dalton
Dalton printed his first published table of relative atomic weights. Dalton had the idea that chemical combination connsists in the interactions of atoms of definite and characteristic weight. He read his theory on October 21, 1803. -
John Dalton
John Dalton printed the first published table of relative weights. -
Amedeo Avogadro
Avogadro's Law states that the relationship between the masses of the same volume of different gases (at the same temperature and pressure) corresponds to the relationship between their respective molecular weights. Therefore the relative molecular mass of a gas can be calculated from the mass of sample of known volume -
Joseph Proust
Proust's was best known for creating elements from water. His law also the law of definite proportions states that a chemical coompund always contains the same proportion of elements by mass. -
Joseph Proust
Joseph Proust published the well known Law of Definite Proportions. -
Dmitri Mendeleev
Mendeleev made a formal presentation to the Russian Chemical Society. His presentation described elements by atomic weight and valence. Mendeleev published his periodic table of known elements. He predicted several new elements to complete the table His predictions were correct therefore qualifying him for majority of the credit in the making of the table. -
Dmitri Mendeleev
Dmitri Mendeleev putting together his periodic table of elements. -
JJ Thomson
Thomson suggested that the fundamental unit that atoms were made of was over 1000 times smaller than the atom itself. Using cathode rays he concluded that they were made of very light, negatively charged particles/electrons which were the building blocks of atoms. -
JJ Thomson
JJ Thomson researching atom structure with his cathode ray -
Marie Curie
Earlier in the year Marie and her husband published a paper that announced the existence of an element they named "polonium". Then December 26 the Curies announced a second element which they named radium for it's radioactivity. -
Marie Curie
Marie Curie and her husband Pierre researching new elements. -
Ernest RutherFord
Rutherford participated in the Gold Foil Experiment in this experiment to look for alpha particles with very high deflection angles, of a type not expected from any theory of matter at that time. It was Rutherford's interpretation of this data that led him to formulate the Rutherford model of the atom in 1911 – that a very small charged nucleus, containing much of the atom's mass, was orbited by low-mass electrons. -
Ernest RutherFord
Ernest RutherFord taking part in the Gold Foil Experiment. -
Hans Geiger
Hans Geiger and John Nuttal discover the Geiger-Nuttal law. It states that short lived isotapes emit more energetic particles than long lived ones. They also performed expeirments that would lead to Rutherford's atomic model. -
Hans Geiger
Hans Geiger performing experiments on short and long lived isotapes. -
Neils Bohr
Neil Bohrs model depicts the atom as small, with a positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, -
Neils Bohr
Neils Bohr researching atoms to find more information on atom structure. -
Enrico Fermi
Enrico Fermi developed the theory of beta decay, postulating that the newly-discovered neutron decaying to a proton emits an electron and a particle which he called a "neutrino". -
Enrico Fermi
Enrico Fermi working on research to support his theory about beta decay.
