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issac newton
issac newton had a proposition that the universe was composed with small solid masses in motion -
daltons theory
dalton suggested new ideas about the atomic structure , using actual experimental observations . he suggested that ...All matter is made of atoms, Atoms are indivisible and indestructible,All atoms of a given element are identical in mass and properties,Compounds are formed by a combination of two or more different kinds of atoms. A chemical reaction is a rearrangement of atoms, and Atoms can be neither created nor destroyed. -
_the cathode-ray tube
j plucker built the first cathode- ray tube or gas discharge tube which opened a new world for scientists to come -
the periodic table
dimitri mendelev created the periodic table based on the past studies and discoveries of former scientists -
g.j stoney
G. J. Stoney proposed that electricity was made of particles called “electrons”. however he was not accredited because it was only an idea -
the birth of the electron
jj tomson published his theory of a sub atomic particle located in all matter.by using a cathode ray-tube , he calculated the ratio of electric charge to mass of the cathode ray. he named this particle, THE ELECTRON -
plum pudding model
jj tomson (the same man who discovered the electron) took a shot at the atomic theory by saying that the atom was like a bed of positively charged pudding with plums or electrons spread out sparingly to give the atom a neutral charge -
rutherfords gold foil experiment
earnest rutherford conducted an experiment to test the structue of the atom -
rutherfords model
by conducting the gold foil experiment, earnest rutherford determined that each atom is made of mostly empty space and also has a central very dense nucleus . rutherford also mentioned that the electrons orbited around the nucleus in a set path at fixed distances -
the nucleus
rutherfod suggested that the nucleus was a small dense positivley charged structure that was located in the center of an atom -
bohrs model
neils bohr composed an atomic model thaat added to the rutherford midel because rutherford`s model could not explain chemical change. bohr suggested that the electron orbits the nucleus in the center at a set distance ,size and energy. bohr also said that an electron jumps to a certain orbit when it gets the correct quantum of energy -
isotopes
aston discovered the existence of isotopes by using a large spectograph (isotopes are varients of an element -
the dual nature of an electron
de broglie suggested that an electron could be either in the form of a wave or in the form of a particle -
the electron cloud
schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. he suggested that the nucleus was still located in the center but instead of the electons orbiting around the nucleus at a fixed distance,they are just buzzing around in certain areas with specific orbitals . this model also supports the idea that electrons can move to different energy levels by gainig a quantum of energy -
the neutron
james chadwick discovered a sub atomic particle similar to an proton.he used alpha particles to determine that these sub atomic particles had a neutral charge . he called these particles neutrons -
the atomic bomb
einstein proposed the idea of purifying uranium -235 to make a weapon of mass destruction einstein and a handful of scientists including neils bohr , began to work on the manhatten project just before the start of world war 2 -
democritus's idea 388 bc
democritus named the smallest piece of matter “atomos,” meaning “not to be cut.” however he had no scientific theory to back his idea up. his theory was based on philosophy only
