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34 Cards in this Set

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  • Back
Believed matter was made up of small spheres
John Dalton
Believed atoms had no change
John Dalton
Expirementally discovered atoms
John Dalton
Believed in indivisble pieces called atoms
John Dalton
Made discoveries in 1803
John Dalton
Believed the world is made up of two things: empty space and atomos
Democritus
Believed individual atoms did not exist
Aristotle
Believed there were five elements: fire, water, earth, air and ether (empty space)
Aristotle
Attempted to make gold out of ordinary elements
Alchemists
First unofficial chemists
Alchemists
Expiremented with different elements and reactions
Alchemists
The Law of Definite Proportions: the ratio of two or more elements in a compound never change
John Dalton
The Law of Multiple proportions: the raito of masses of elements combined together can be expressed in whole numbers
John Dalton
The Law of Conservation of Mass: Matter can be altered but never created of destroyed
John Dalton
Believed atoms are made up of charged particles
JJ Thomson
Used a cathode ray tube to generate a stream of electrons, he used an electrical field to bend the stram of electrons
JJ Thomson
Plum Pudding Model: Negative electrons embedded in a positive sphere
JJ Thomson
Conducted oil drop expirement to determine magnitude of the electron charge. ONe electron = 9.11 x 10^-31 kg
Robert Milikan
Found the nucleus and determined it was positively charged, very dense and made up most of the mass
Lord Rutherford
Determined atoms were made up of mostly empty space
Lord Rutherford
Found that some particles bounced off of something in the atoms
Lord Rutherford
Discovered high energy particles with no charge in nucleus (neutrons)
James Chadwick
Expiremental difference in mass of an atom and the number of protons
James Chadwick
Found that electrons must move in concentric circles (orbits) around the nucleus
Niels Bohr
Distinct Energy Levels:
1st Layer - 2 electrons
2nd Layer - 8 electrons
3rd Layer - 18 electrons
4th Layer - 32 electrons
Niels Bohr
1913
Niels Bohr
1932
James Chadwick
1909
Lord Rutherford
1899
Robert Milikan
1897
JJ Thomson
1803
John Dalton
300- 1400 AD
Alchemists
382 - 322 BC
Aristotle
400 BC
Democritus