smallest piece of matter, not to be cut, indivisible
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DEMOCRITUS
Believed that matter could not be divided indefinitely?
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Aristotle
Believed that matter could be divided into smaller and smaller pieces forever
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John Dalton
Proposed the hook and eye model of atom based on experimentation and not on pure reason; There are elements that can be easily combined/separated; Also believed that atom is the smallest unit
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Law of Conservation of Mass
atoms cannot be created nor destroyed
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atomic theory (1808)
all matter is made of atoms
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Hook and Eye Model of Atom
It is crucial for the successful interaction of two atoms.
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JOSEPH JOHN THOMSON
First proposed that atoms are divisible; Found that atoms could sometimes eject a far smaller negative particle, the electron, while working with a cathode ray tube
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1897
When was electron discovered?
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Corpuscles
The term before for electrons
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The Plum Pudding Model of Atom
JJ Thomson developed this model of atom
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negative electric charges (electrons)
The plums represented what?
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shapeless mass of uniform positive electrification
The pudding represented what?
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ERNEST RUTHERFORD
He introduced that the positive electrification mentioned by Thomson is a small dense center he named nucleus; He is considered the Father of Nuclear Physics; He also discovered the proton
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1911
When was nucleus discovered?
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1919
When was proton discovered?
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Nuclear Model of Atom
describes the atoms as containing a small, dense, + charged center, known as the nucleus, with - electrons orbiting a nucleus in set, predictable paths
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Ernest Rutherford
Who discovered the Nuclear Model of an Atom?
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Niels Bohr
A Danish scientist that proposed an improvement by placing each electron in a specific energy level
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1913
When did Niels Bohr proposed an improvement by placing each electron in a specific energy level?
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quantum of an energy
Electrons can move up a level if given enough energy. What is the so-called energy?
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quantum leap
Electrons can move up a level if given enough energy. What is the so-called movement of electrons?
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The Planetary Model of Atom
Electrons move in definite orbits around the nucleus, much like planets circle the sun . These orbits, or energy levels, are located at certain distances from the nucleus.
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Niels Bohr
Who proposed The Planetary Model of Atom?
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Erwin Schrödinger
An Austrian physicist that used mathematical equations to describe the likelihood of finding an electron in a certain position; Also introduced the concept of sub-energy levels (s,p,d,f...)
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Quantum Mechanical Model
Describes the likelihood of finding an electron in a certain position. This atomic model is known as the
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Electron Cloud Model
Other term for Quantum Mechanical Model
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1926
When was Quantum Mechanical Model proposed?
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James Chadwick
Who discovered the neutron? He was also awarded a nobel prize in physics for this discovery.
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