Atomic Theories Timeline

murmerlastΠολεοδομικά Έργα

16 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

55 εμφανίσεις

Atomic Theory

When looking at the
History of the Atom.

The Atom was always
Neutral.

Let’s Take a Trip Through Time!



Democritus

460


370 B.C.


Greek Philosopher


There are various basic
elements from which all matter
is made


Coined the term “atom” which
means indivisible


Everything is composed of
small atoms moving in a void


Some atoms are round, pointy,
oily, have hooks, etc. to
account for their properties


Ideas rejected by leading
philosophers because void =
no existence

Demokritos c. 460
-
370 BC

“The material cause of all things that exist
is the coming together of atoms and void.
Atoms are too small to be perceived by
the senses. They are eternal and have
many different shapes, and they can
cluster together … By aggregation they
provide bulky objects that we can
perceive with our sight and other
senses… There is no void in atoms, so
they cannot be divided.”

“Atomos” = “indivisible”

First Concept of an Atom





Antoine Lavoisier

1743
-
1794


French



Known as the “Father of
Modern Chemistry”


Came up with Law of
Conservation of Mass


He had discovered that
mass is conserved within
a chemical reaction. The
mass of the products of a
chemical reaction is
always the same as the
mass you started with.




John Dalton

1766
-
1844


Born in England


Introduced his ideas in 1803


Proposed the “Atomic Theory”



Each element is composed of
extremely small particles called
atoms


All the atoms of a given element are
identical, but they differ from those
of any other element


Atoms of different elements have
different properties including
different masses


Compounds are formed when
atoms of more than one

kind of
atom combine


Taught at University of Manchester,
was said to “see things differently
than others”

Dalton’s Model





The Cannonball Model



Michael Faraday

1791
-
1867


Born in England


Coined term “electrolysis”

used electricity on
solutions to split water
(1832)


Also moved a wire
through a magnet to
create an electrical
current which lead to
invention of generators
(Industrial Revolution)







James Clerk Maxwell

1831
-
1879


Developed the
Maxwell
-
Boltzmann
kinetic theory of
gases (1866). This
theory showed that
temperatures and
heat involved only
molecular movement.


Electromagnetic
Fields


Dmitri Mendeleev

1834
-
1907


Russian


Developed the Periodic Table
(1869)


His first Periodic Table was
compiled on the basis of arranging
the elements in ascending order of
atomic weight and grouping them
by similarity of properties.


Left space for new elements, and
predicted three yet
-
to
-
be
-
discovered elements including
eke
-
silicon and eke
-
boron.


His table did not include any of the
Noble Gases, however, which had
not yet been discovered.



Henri Becquerel

1852
-
1908


Discovery of Radioactivity
(1896)


Coined the term “X
-
Ray”


For his discovery of
spontaneous radioactivity
Becquerel was awarded
half of the Nobel Prize for
Physics in 1903, the other
half being given to Pierre
and Marie Curie for their
study of the Becquerel
radiation


J.J. Thomson

1856
-
1940


Discovered electron
1897


Cathode Ray
Experiment


Plum Pudding model
1904


Electrons in a
soup

of
positive charges


Discovered isotopes 1913


Noble Prize in Physics
(1906)

Plum Pudding Model



Marie
Sklodowska

Curie

1867
-
1934


Born in
, Warsaw, Poland
(November 7, 1867)


Studied Uranium


Discovered Radium and
Polonium


She worked with radioactivity,
x
-
rays in medicine, and
changes in the atomic nucleus.
Curie’s discovery in changes in
the atomic nucleus led the way
toward the modern
understanding of the atom as
an entity that can be split to
release enormous amounts of
energy.







Marie Curie (con’t)


Awarded Noble Prize in Physics (with H. Becquerel and
Pierre Curie) in 1903. “in recognition of the extraordinary
services they have rendered by their joint researches on
the
radiation

phenomena discovered by Professor Henri
Becquerel."



Awarded Noble Prize in Chemistry in 1911. "in
recognition of her services to the advancement of
chemistry by the discovery of the elements radium and
polonium, by the isolation of radium and the study of the
nature and compounds of this remarkable element."



Albert Einstein

1879
-

1955


Jew born in Germany


Developed the Theory of
Relativity and specifically
mass
-
energy
equivalence,
E

=

mc

2


Received the 1921 Nobel
Prize in Physics "for his
services to Theoretical
Physics, and especially
for his discovery of the
law of the Photoelectric
Effect.



































Albert Einstein


Became a United States Citizen in 1940


With Leo Szilard wrote a letter to then President
FDR on Aug 2, 1939 that lead to the Manhattan
Project. (Einstein did not help develop the
Atomic Bomb other than to sign the letter)


Manhattan Project
-
brought together top
scientists from the US, Britain, Canada and
refugees of Nazi Germany to develop Nuclear
Weapons

Robert Millikan

1868
-
1953


Born in Morrison, Illinois


“Oil Drop Experiment” (1909)
Determined the charge and
mass of an electron


Set out to determine the
measurement of electrical
charge with the use of x
-
rays.
In the process of doing so he
discovered the most
persuasive evidence to
support that electrons were
basic particles, and that they
all had the equal mass and
charge.

Ernest Rutherford

1871
-
1937


Born in New Zealand


Nuclear Model
1910


Gold Foil Experiment


Atom is mostly empty
space


Nucleus has a positive
charge


Noble Prize in Chemistry
(1908)
“for his investigation into
the disintegration of the elements,
and the chemistry of radioactive
substances”



Ernest Rutherford

1871
-
1937


doctoral student of
Thomson 1895
-
1989


Physics Chair at McGill from
1898
-
1907 before returning
to England and teaching at
Manchester University


takes
over Cavendish Chair
of Physics from Thomson in
1919

Alpha Particle Experiment



Show the Gold Foil Experiment Animation

Rutherford Model



Nuclear Model

H. G. J. Moseley

1887
-

1915


English Physicist


Using x
-
ray tubes, determined
the charges on the nuclei of
most atoms.


He wrote “The atomic number
of an element is equal to the
number of protons in the
nucleus”.


This work was used to
reorganize the periodic table
based upon atomic number
instead of atomic mass. (1913)

Niels Bohr

1885
-
1962


Danish


Planetary Model
1913


Nucleus surrounded by
orbiting electrons at
different energy levels


Electrons have
definite
orbits


Utilized Planck’s
Quantum Energy

theory


Worked on the Manhattan
Project (US atomic bomb)

Bohr’s Model



Quantum Energy Levels

-
Atomic Model has
electrons found in
specific energy levels.

Bohr Model for Nitrogen



Prince Louis
-
Victor deBroglie


1892
-
1987


educated and worked in
France
-

BA in 1913 &
graduate work after
serving for France in WWI


his 1924 doctoral thesis
introduced “wave
mechanics”
-

the idea that
the electron could be
treated as a wave


1929 Nobel Prize in
Physics

Werner Heisenberg 1901
-
1976


Born in Wurzburg, Germany


1923
PhD in Munich


1924
-
’25 works with Bohr in
Copenhagen


establishes “quantum mechanics”
when only 23 years old in 1925
-

includes
Uncertainty Principle


1932 Nobel Prize in Physics


1941 director of Kaiser Wilhelm
Institute in Berlin
-

captured by US
troops at end of WWII & sent to
England; returns to Germany after
the war

Erwin Schr
ød
inger 1887
-
1961


Born and educated
in Vienna;
serves in Austrian Army in WWI


1926 publishes
“wave
equation”

model of electrons


Goes to Germany in 1927 but
leaves in 1933 with rise of Nazis;
ends up in Austria in 1937;
recants
opposition
to Nazis but is
harassed and escapes in 1938


1933 Nobel Prize in Physics with
Dirac


1940 establishes Institute for
Advanced Studies in Dublin

Ernst Schrödinger 1887
-
1961



Quantum
Mechanical Model
or
the Wave Mechanical Model or
the Cloud Model 1926

The accepted way we presently
look at the atom


Electrons found in a region
(cloud) around the nucleus


Electrons
are in
probability
zones
called
“orbitals”,

not
orbits and the location
cannot be pinpointed


Electrons are
particles and
waves at the same time


Developed quantum
numbers based on theories
of Einstein and Planck



Werner Heisenberg 1901
-
1976

Wave


Mechanical Model



James Chadwick

1891
-
1974


Born in England


Made the important
discovery of neutrons
(1932). A particle in an
atom that held a neutral
charge, neither positive
nor negative. This
discovery helped tell the
difference between the
atomic number and the
mass number.


Was awarded the Nobel
Prize in Physics in
1935


A student of Rutherford














Otto Hahn 1879


1968

Fritz
Strassmann

1902
-

1980


Worked with
Lise

Meitner in
Berlin, until Meitner was forced to
flee Nazi Germany


Experimented by bombarding
uranium’s heavy nuclei with
neutrons
-

got unexpected results


lighter elements, such as
barium, were produced.



Hahn is regarded as "the
father of nuclear chemistry"
and the "founder of the atomic
age".

Lise

Meitner 1878


1968

Otto Robert Frisch 1904
-

1979


Meitner, a physicist, worked for
years with chemists Hahn and
Strassmann

to study the
behavior of nuclei


Meitner, working with her
nephew, Frisch, were the first
to understand that uranium
nuclei could be split when
bombarded by neutrons.


Calculated the amount of
energy released each time a
uranium nucleus undergoes
fission (an example of E = mc
squared at work)

Glenn Seaborg

1912
-
1999


American born in Ishpeming,
Michigan


Through the years of 1937 to
1939 he published many
scientific papers. He also
discovered 10 atomic elements
and one was even named after
him,

"
seaborgium
."


Noble Prize in Chemistry
(1951) w/ Edwin McMillan “for
their discovery in the chemistry
of the
transuranium

elements”


Suggested a change in the
layout of the Periodic Table

Glenn Seaborg (con’t)


Appointed Chancellor of the University of
California at Berkeley
in 1958


Named Marv Levy as the Head Football Coach in 1960 (a position he held
until1963
)

"In 1944, Seaborg formulated the 'actinide concept' of heavy element electronic
structure which predicted that the actinides


including the first eleven
transuranium

elements


would form a transition series analogous to the rare
earth series of lanthanide elements. Called one of the most significant changes
in the periodic table since Mendeleev's 19
th

century design, the actinide concept
showed how the
transuranium

elements fit into the periodic table."

Headed the plutonium work of the Manhattan Project (1942
-
1946)

Co
-
discoverer of plutonium and all further
transuranium

elements through element
102

Between 1961 and 1971, Seaborg was the chairman of the AEC, a predecessor
agency of the Department of Energy (DOE). Seaborg was active in
national
service
, advising ten presidents from Franklin D. Roosevelt through George H.
W. Bush.


Enrico Fermi

1901
-

1954


Italian


Used neutron to split the
nucleus of uranium atom
(First controlled chain
reaction)


Fled Italy in 1938 and
became a naturalized
American


Lead Manhattan Project
at University of Chicago

Manhattan Project


Started because F.D.R was
persuaded by Einstein and other
scientist after
Hilter’s

assault on
Poland


Brought together the top scientists
from US., England, Canada, and
refugees of Nazi Germany


Under the leadership of
Enrico

Fermi, took place at the University
of Chicago’s Stagg Field (Football
Field)


On July 16, 1945 in a desert near
Alamogordo, New Mexico experts
detonated the first atomic device.

World War II


December 7, 1941


Pearl Harbor


Potsdam Conference, held in
Berlin in July
1945


President Truman with J.
Stalin issue a ultimatum to Japan,
surrender or be destroyed


August
6, 1945


Dropped bomb on Hiroshima


August 9, 1945



Dropped bomb on
Nagasaki


August 10, 1945



Japan Surrendered




Review of Atomic Models

1803


Dalton

Cannonball Model

1897


Thomson

Plum pudding Model

1909


Rutherford

Nuclear Model

1913


Bohr

Planetary Model

Present

Wave


Mechanical Model