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14 Cards in this Set

  • Front
  • Back
Democritus: Greek Philosopher 100 bc
mater could not be divided forever

smallest piece indivisible or

ATOMOS: not to be cut,indivisible
Dalton's Model 1800's
Atomic Theory :

all elements made of atoms

atoms same element same
atoms different elements different
atoms indestructible & indivisible
Thomson's model
atoms were divisible

discovered smaller particles existed

atomic model: pudding like material -
Rutherford's Model
nucleus : center of atom

postive charges in nucleus

negative charges scattered outside
Bohr's Model
Improved Rutherford's Model

Electons move in orbit around nucleus
Wave Model:Present
based on wave mechanices

electons do not move in a definite pattern like planets
location based on how much energy electon has
atoms small +nucleus, large # - elect.
making atom nuetral
Subatomic particle
particle smaller than a atom
postive charged particle
neutrally charged particle
negative charged particle
core of the atoms

99% of the mass

100,000 small than the atom
atomic mass unit
amu: special unit use to measure subatomic particle because the mass is so small

Proton 1 amu
neutorn 1 amu
electron 1/1836 amu
Atomic Number: indentifies element
number of protons in the nucleus

all elements have different #, which distinguishes the element.

Uranium has the most 92
Mass Numer of Atom
Sum of proton and neutrons