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Democritus
Postulated the theory of atoms and void; the universe is made
up of empty space and a nearly infinite number or invisible
particles differing in arrangement, form, and position. He
stated that all all matter is composed of indivisible atoms. -
Antoine Laurent Lavoisier
French chemist, who is considered the founder of modern chemistry. He clarified that an element cannot be broken down and he devised a theory of the formation of chemical compounds from elements. -
Joseph Proust
Joseph Proust Scientist: Joseph Louis Proust
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www.MirusFutures.com Home > Library > Science > Dictionary of Scientists
French chemist (1754%u20131826) Proust was born the son of an apothecary at Angers in northwest France. He studied in Paris and became chief apothecary at the Saltptrire Hospital. In 1789 he went to Madrid to become director of the Royal Laboratory under the patrona -
John Dalton
English chemist who proposed the Atomic Theory which
stated that all matter was made of small indivisible
particles called atoms. These atoms possess unique
characteristics and weight for different elements.
He also stated that three types of atoms exist: simple.
(elements), compound (simple molecules), and complex
(complex molecules). -
William Crookes
In 1875 he invented the radiometer, an evacuated transparent bulb that has an arrangement of vanes, black on one side and silvered on the other, that spins when placed in a light which caused an unequal heating of the gases left in the bulb near the black and the silver vanes). -
Henri Becquerel
A French physicist who found that rays coming from a
uranium ore affected a photographic plate like X-rays did.
The rays were not from an external source and were more
powerful than those from a sample of pure uranium. His
experiment led to the discovery of natural radioactivity -
J.J. Thomson
First to measure the electron. Developed the
plum-pudding model of the atom. He described the atom as a
slightly positive sphere with small electrons inside. -
J.J. Thomson
J J THOMSON%u2019S CATHODE RAY EXPERIMENT -
Marie and Pierre Curie
They spent much of their careers studying radioactivity examining the particles and energy produced as radioactive atoms decayed, and in the process learned about the building blocks of matter. They established that the heavy element thorium was radioactive and discovered two new elements. -
Ernest Ruthford
Ruthfod's Nuclear atom model -
Robert Millikan
Discovered the charge of an electron with his oil drop
experiment. -
Ernest Rutherford
Inferred a small, dense, positively-charged nucleus as the
result of the alpha particle scattering gold foil experiment. -
Neils Bohr
A Danish physicist who stated that electrons could only
orbit the nucleus in succesively larger orbits around the
nucleus. The outer orbits could hold more electrons. The
electrons in the outermost shell determine the properties of
the atom. He also inferred that when an electron moves from
an outer orbit to an inner orbit it gives off a quantum of energy,
a photon, in the form of light. -
Neils Bohr
Planetary System Model -
H.G.J. Moseley
Using x-ray tubes, determined the charges on the nuclei of most atoms. He wrote"The atomic number of an element is equal to the number of protons in the nucleus". This work was used to reorganize the periodic table based upon atomic number instead of atomic mass. -
James Chadwick
Discovered the neutron.
