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Democritus
Existed in 500 B.C.
Democritus believed that all matter consisted of extremely small particles that could not be divided. -
Existed in 500 B.C.
Aristotle did not think there was a limit to the number of times matter could be divided.
He described matter by using a model. -
George Hadley's Life
Hadley was an English lawyer and amateur meteorologist who proposed the atmospheric mechanism by which Trade Winds are sustained. -
Dalton pictures atoms as tiny, indestructible particals, with no internal structure.
Dalton gathered evidence for the existence of atoms by measuring the masses of elements that combine when compounds form. -
A British chemist, studied under Rutherford and brilliantly developed the application of x-ray spectra to study atomic structure.
Moseley's discoveries resulted in more accurate positioning of elements in the Periodic Table by closer determination of atomic numbers. -
A British scientist, discovers the electron, leading to his "plum-pudding" model. He pictures electrons embedded in a shere of positive electric charge.
Thomson used a device. At the center of the device is a sealed glass tube from which most of the air has been removed. There is a metal disk at each end of the tube. Wires connect the metal disks to a source of electric current. When the current is turned on, one disk becomes negitively charged and the other disk becomes positively charged. -
Hantaro
A Japanese physicist, suggests that an atom has a central nucleus. Electrons move in orbits like the rings around saturn. -
Marsden could figure out the path of an alpha particles after it passed through gold.
Marsden aimed a narrow beam of alpha particles at the gold. The screen around the gold was made of a material that produced a flash of light when struck by a fast-moving alpha particle. -
Rutherford states that an atom has a dense, positively charged nucleus. Electrons move randomly in the space around the nucleus.
Marsden and Rutherford both worked together on The Gold Foil experiment. -
Niel Bohr
Bohr says that the electrons move in a spherical orbits at fixed distances from the nucleus. -
broglieBroglie proposes that moving particles like electrons have some properties of waves.
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Schrodinger describes the motion of electrons in atoms. His work leads to the electron cloud model.
Develops mathematical equations. -
ChadwickA British physicist, confirms the existence of neutrons which have no charge. Atomic nuclei contain neutrons and positively charged protons.
