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Period: 322 to
Aristotle
384 BC - 322 BC
ristotle’s theory made a great generalization of all matter of the four elements: fire, water, earth, and air. He also believed that there were four qualities to these elements: dryness, hotness, coldness, and moistness. -
442
Democritus
442 BC he theorized that 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 -
Period: to
Antoine-Laurent de Lavoisier
"The Father of Modern Chemistry". A French chemist who proved the conservation of matter and explained the mysteries of fire.
1773 he proved that sulfur was an element rather than element
He gave the name "Oxygen to the element in 1778 and in 1783 he gave Helium its name.
He also helped create the metric system and put to the most exstensive list of elements -
John Dalton
English chemist who stated the Atomic Theory which
stated that all matter was composed of small indivisible
particles called atoms. These atoms possess different
characteristics and weight for different elements.
He also stated that three types of atoms exist: simple
(elements), compound (simple molecules), and complex
(complex molecules). -
James Clerk Maxwell
His bggest acheivement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory -
Marie Skłodowska-Curie
Studied and identified radioactive elements. She was awarded with the Nobel Prize in physics in 1903 and the same for chemsitry in 1911 (The first to do so) -
J.J Thompson
First to measure the electron. Developed the
plum-pudding model of the atom. Describes the atom as a
slightly positive sphere with small electrons inside. -
Max Karl Ernst Ludwig Planck
German physicist who discovered quantum physics, initiating a revolution in natural science and philosophy. He is given the credit of as the founder of quantum physics. -
Robert Andrews 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. -
Henry Gwyn Jeffreys Moseley
Moseley's outstanding contribution to the science of physics was the justification from physical laws of the previous empirical and chemical concept of the atomic number -
Werner Karl Heisenberg
Made contributions to quantum mechanics and is best known for asserting the uncertainty principle of quantum theory. In addition, he made important contributions to nuclear physics, quantum field theory, and particle physics. -
Erwin Rudolf Josef Alexander Schrödinger
Developed wave mechanics which describe the behavior
of quantum systems for bosons. ( subatomic particles that obey Bose–Einstein statistics) -
Sir James Chadwick
Discovered the neutron. (He also helped in the Manhattan Project a.k. the atomic bomb) -
The Modern Atomic Model
Electrons are in constant motion around the nucleus, protons and neutrons jiggle within the nucleus, -
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 emits a quantum of energy,
a photon, in the form of light.
