Download Atomic Theory Notes

Name: ____________________________________
HISTORY OF THE ATOMIC MODEL
1800
1950
1900
2000
JOHN DALTON
DMITRI MEDELEEV
JJ THOMSON
ROBERT MILLIKAN
ERNEST RUTHERFORD
NIELS BOHR
(1766-1844)
(1834-1907)
(1856-1940)
(1868-1953)
(1871-1937)
(1885-1962)
 Dalton Model of
the Atom (Billiard
Ball Model) 1803
 Atoms are the
tiniest particle
 Atoms of the same
element are the
same
 Atoms of different
elements are
different
 Atoms cannot be
created, destroyed,
or divided
 Periodic Table 1869
 Grouped like
elements together
based on physical
properties into 7
groups
 Placed elements
based on atomic
mass
 Discovered
properties were a
function of atomic
mass
 Predicted missing
elements
 Discovered the
electron using
cathode ray tubes
and an electric field
 Found the electron
to be negatively
charged
 Plum Pudding
Model 1897
 Oil drop experiment
1908-1917 –
atomizer sprayed oil
into chamber, falling
through a pinhole,
atoms are ionized
and attracted to the
positively or
negatively charged
plate
 By varying the
charge, an equation
could be used to
determine the
charge of the
electron.
 Built on JJ
Thomson’s Plum
Pudding Model to
create Rutherford’s
Model 1910
 Gold Foil
Experiment
 Discovered that
atoms are mostly
empty space - a
positive nucleus
with a large electron
cloud
 Applied quantum
theory to
Rutherford’s atom
and determined that
electrons travel in
discrete (quantized)
orbits or energy
levels or shells
 Discovered that the
emission of light
occurs when
electrons move from
a higher orbital to a
lower one
 Developed the Bohr
Model 1920
Name: ____________________________________
HISTORY OF THE ATOMIC MODEL
1800
1950
1900
2000
ERWIN SCHRODINGER
JAMES CHADWICK
LISE MIETNER
MARIA GOEPPART-MAYER
MURRAY GELL-MANN
(1887-1961)
(1891-1974)
(1878-1968)
(1906-1972)
(1929-current)
 The Schrodinger wave
equation
 Theorized that
electrons move like
waves
 Replaced Bohr’s well
defined orbits with
probability “clouds”
 Electron Cloud Model
1926
 Proved the existence
of neutrons (neutral
particles with mass
located in the
nucleus) 1932
 Neutrons make up ~
½ the mass of an
atom
 Discovered the process
of nuclear fission 1939
through the theory of
Bohr’s “liquid drop”
model

 Discovered the nuclear
“Magic Numbers” – the
specific ratio of protons
and neutrons that enable
an atom to be stable
1948
 These magic numbers
also correlate to a full
outer shell of electrons
 Helped to explain the
idea of isotopes
 2nd women to win a
Nobel Prize
 Discovered quarks which
make up protons and
neutrons 1961
 Proposed a new quantum
property of particles called
“the strangeness number”