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460
Democritus
Date: 460-370 BC
He continued the work of his mentor, Leucippus Formulated an atomic theory similar to modern science’s understanding of the atom.How this contributed to our understanding of the atom would be his theory suggested that atoms can’t be destroyed and exist in a void. Atoms only differ in shape, position and arrangement. Hs discovery was often questioned because he could not explain the chemical side of his 'atom' idea. -
Antoine Lavoisier
Lavoisier discovered the Law of Conservation of Mass. -
John Dalton
He said that elements consisted of tiny particles called atoms, and that the reason an element is pure is because all the atoms of an element are identical, and that they have the same mass. His theory also stated that atoms of each element were different from one another; in particular, they had different masses which helped lead to his conclusion that each atom has its own characteristic weight.He also that compounds were atoms of different elements put together. This helped classify atoms. -
Gold Foil Experiment
Gold foil experiment consisted of a series of tests in which a positively charged helium particle was shot at a very thin layer of gold foil. -
Dmitri Mendeleev
Dmitri was a Russian chemist who discovered the peroiodic law and developed the periodic table. -
J.J Thomson
He invented the Cathode Ray. When high energy was moved from the negative cathode plate through a vacuum sealed container to a positive plate, it created a beam of electrons. This resulted in the Plum Pudding atomic model. In the model, Thompson thought all of the particles he saw were clumped together. This allowed solids to be made when harder substances were clumped together. -
Cathode Ray Tube
This Cathode Ray Tube was inverted by J.J. Thomson and this tub is a vacuum tube containing an electron gun and a florescent screen used to view images. -
Plum Pudding Model
He discovered the Plum Pudding Model. He set this model to help people visualize and learn about electrons. In a plum pudding, the pudding is positively charged while the plums, dotting the dough, are negatively charged electrons. -
Robert Millikan
Millikan is famous for his measurement of the charge of an electron and his work on the photoelectric effect. How this contributed to our understanding of the atom: Using an oil drop experiment Millikan measured the charge of an electron. -
Law of Conservationa and Mass
Physics and chemical engineering -
Ernest Rutherford
He made up the Rutherford model, stating that a very small positively charged nucleus was orbited by electrons. It supported Nagaoka’s model of the atom. -
Bohr Planetary Model
Atom that has all protons and neutrons clustered together in the nucleus at the center of the atom. -
Henry Moseley
Created the application of X-ray spectra to study atomic structure. -
Electron Cloud Model
States that the elctrons do not have a specific spot in the arom. They are anywhere around the nucleus. -
Neils Bohr
Fundamental contributions to the understanding of atomic strucutre and quantum mechanics. How this contributed to our understanding of the atom: By expanding on Rutherford's earlier theory, Bohr published his theory which suggested that electrons travel in specific orbits around the nucleus, that outer orbits can hold more elctrons than the inner orbits and that these orbits determine the chemical properties of the atom. -
Quantum Mechanical Model
Cereated by Erwin Schrodinger, the quantum mechanical model says that the posistion and momentum of an electron cannot be determined at the same time. and that the number of energy levels for electrons is a result due to their wave like properties. -
James Chadwick
Famous for his discovery of the neutron/ How this contributed to our understanding of the atom: Chadwick discovered the neutron, named because of its lack of electrical charge, which was previously an unknown particle in the nucleus of an atom. -
Erwin Schrodinger
Fixed the puzzle about the electron arrangement. He stated that electrons behave more like waves and for this reason couldn't be precisely calculated. He also theorized that each electron had a sub shell equal to the number shell number.
