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460
Democritus
From 460 to 370 B.C. Democritus was one of the first scientist to study the atom and is considered to be the father of the atom. He stated that all atoms are indivisible, small, undestructable particles. Democritus additionally believed there are an infinite number of atoms as well as different types that vary in shape as well as size. -
Law of Conservation of Mass
The mass of an isolated system stays constant over time which is equivalent to the conservation of energy; when mass or energy is closed within a system and not allowed in or out it's quantity cant change time. -
Antoine Lavoisier
Lavoisier showed that diamonds and graphite were both forms of carbon by burning each to make carbon dioxide. He showed that candles burning and humans working both exhale carbon dioxide, pointing the way to understanding biochemistry and metabolism. John Dalton deduced modern atomic theory in 1803 based upon the quantitative work of Lavoisier. -
John Dalton
Daltons Atomic Theory was that all matter is composed of atoms, atoms cannot be made or destroyed, all atoms of the same element are identical, different elements have different types of atoms, chemical reactions occur when atoms are rearranged,
and compounds are formed from atoms of the constituent elements. -
Daltons Atomic Theory
Daltons Atomic Theory developed the first useful atomic theory of matter. Dalton concluded that evaporated water exists in air as independent gas. -
Demitri Medelvee
Arranged the elemets into 7 groups with the same properties. Discovered properties of elements "were periodic functions of their own atomic weights" known as Periodic Law. -
Cathode Ray Tube
A cathode ray tube is a glass tube that has a wire passing through both ends. An electrical current is passed through this wire from the cathode (negative terminal) to the anode (positive terminal). Cathode rays travel along the wire in a vacuum, producing a beam of light.Thomson thought that the cathode rays had a negative charge.In 1895, Jean Perrin set out to confirm Thomson's speculation that cathode rays carried a negative charge. -
J.J Thomson
J.J Thomson discovered the electrons, he proved his theory using the cathode ray tube. -
Plum Pudding Atomic Model
The Plum Pudding Model was introduced by J.J Thomson. Today’s atom has a very dense and very small positive charged nucleus. The Plum Pudding Model represents why most atoms were neautral. -
Robert Milikan
Robert Milikan determined the mass of the electron, and the unit charge of the electron in 1909 using his oil drop expirement. -
Rutherford Model
Rutherford made the Gold goil Expirement in 1909. He made this model to deminstrate how the alpha particles pass straight through the gold like electrons would. This showed that the atom contained a positive charge and most of the mass. The nucleus is approcimately 100,00 times smaller that the atom and the atom is 99.99% empty space. -
Gold Foil Expirement
Earnest Rutherford is credited with this expirement, which involved firing radioactive particles through extremely minute foils that were mostly gold. They were detected by using zinc sulfide coated screens. This lead to many deflected while some passed through the screen which caused rutherford to theorize that most of the atom was made up of empty space. -
Earnest Rutherford
Earnest Rutherfords atomic theory describes the atom as having a central positive nucleus surrouned by negative orbitting electrons. Most of the mass of an atom was contained in the small nucleus and the rest of the atom is mostly empty space. -
Bohr Planetary Model
The Bohr model shows that the electrons in atoms are in orbits of differing energy around the nucleus. -
Neils Bohr
Neils Bohr proposed that electrons are arranged in concentric circular orbits around the nucleus, known as the planetary model. -
Electron Cloud Model
Shows the possible location of electrons in an atom, and shows that the electrons are found on orbitsals around the nucleus and this model shows us all that. -
Henry Moseley
Discovered that the energy of x-rays emitted by the elements increased with each positive charge on the nucleus. -
Quantum Mechanical Model
A model of atomic structure that is based on mathematics and can be used to explain observations made on complexations. -
James Chadwick
James Chadwick descovered the neutron in 1932 which led to the discovery of fission nd to the atomic bomb. -
Erwin Shrodinger
Erwin Shrodinger proposed that electrons are arranged in concentric circular orbits around the nucleus. Erwin used math equations to describe the finding of an electron in a specific position.
