Transcript ATOMIC THEORY

ATOMIC THEORY
ATOMIC STRUCTURE
ATOMIC THEORY
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DEMOCRITUS - 400BC PROPOSED
THE FIRST ATOMIC THEORY.
HE SUGGESTED THAT THE WORLD
WAS MADE OF TWO THINGS,
EMPTY SPACE AND TINY PARTICLES
HE CALLED ATOMS.
ATOMIC THEORY
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JOHN DALTONDEVELOPED THE
FIRST MODERN
ATOMIC THEORY
ATOMIC THEORY
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ALL MATTER IS COMPOSED OF VERY SMALL PARTICLES CALLED
ATOMS
ATOMS CANNOT BE BROKEN DOWN INTO SMALLER PARTICLES.
ALL ATOMS OF AN ELEMENT WERE EXACTLY ALIKE AND ATOMS
OF DIFFERENT ELEMENTS ARE QUITE UNLIKE.
ATOMS CAN UNITE WITH OTHER ATOMS IN SIMPLE RATIOS TO
FORM COMPOUNDS
ATOMIC THEORY
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ANTOINE LAVOSIER-CONDUCTED AN
EXPERIMENT THAT PROVED THE LAW OF
CONSERVATION OF MASS
JOSEPH PROUST-OBSERVED THAT
SPECIFIC SUBSTANCES ALWAYS CONTAIN
ELEMENTS IN THE SAME RATIO BY MASS.
THIS PRINCIPLE IS KNOWN AS THE LAW
OF DEFINITE PROPORTIONS
(COMPOSITION)
ELECTRON DISCOVERY
JJ THOMSON-1897
DID SOME SKILLFUL
RESEARCH ON
CATHODE RAYS.
 AS A RESULT HE IS
GENERALLY CREDITED
WITH THE DISCOVERY
THAT THE RAYS
CONSIST OF
ELECTRONS.
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EARLY RESEARCH ON ATOMIC
PARTICLES
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Robert Millikan- Obtained the first
accurate measurement of an
electron’s charge.
The Oil Drop Experiment
EARLY RESEARCH ON ATOMIC
PARTICLES
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Rutherford-discovered the proton
using cathode ray tubes and alpha
particles.
James Chadwick- Credited with
the discovery of the neutron.
ISOTOPES AND ATOMIC
NUMBER
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JJ Thomson – observed what
seemed to be two kinds of neon
atoms, chemically alike but different
in mass.
Atoms of the same element that
differ in mass are called isotopes.
Isotopes have the same number of
protons but different numbers of
neutrons.
NEON ISOTOPES
ISOTOPES AND ATOMIC NUMBER
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Henry Moseley- Studied x-rays
produced in x-ray tubes with
different metal anodes.
The wavelength depends on the
number of protons in the nucleus
and is always the same for a given
element.
The number of protons in an atom
is called the atomic number.(Z)
ATOMIC STRUCTURE
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Neils Bohr –
Proposed the
Planetary Model
of the atom.
NUCLEAR THEORY OF THE ATOM
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1912-1913
Rutherford brought
together a brilliant
team of physicists
whose experiments
revealed the modern
structure of the atom.
The Nuclear Theory
of the Atom
Nuclear Theory
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Geiger and Marsden-Members of
the team of Physicists brought
together by Rutherford who
conducted the Gold-Foil
Experiment.
THE THREE MAIN SUBATOMIC
PARTICLES