history of the atom
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History of the Atom. Scientists and Their Contribution to the Model of an Atom. History of the Atom - Timeline. Antoine Lavoisier makes a substantial number of contributions to the field of Chemistry. J.J. Thomson discovers the electron and proposes the Plum Pudding Model in 1897. - PowerPoint PPT PresentationTRANSCRIPT
History of the AtomScientists and Their Contribution
to the Model of an Atom
Democritus proposes
the 1st atomic theory
460 – 370 BC
History of the Atom - Timeline Antoine Lavoisier
makes a substantial number of
contributions to the field of Chemistry
1766 – 1844
John Dalton proposes his
atomic theory in 18031743 – 1794
0
1856 – 1940
J.J. Thomson discovers the electron and proposes the Plum Pudding Model in 18971871 – 1937
Ernest Rutherford performs the Gold Foil Experiment in 1909
1885 – 1962
Niels Bohr proposes the Bohr Model in
19131887 – 1961
Erwin Schrodinger describes
the electron cloud in
1926
1891 – 1974
James Chadwick
discovered the neutron in in 1932
1700
s18
00s
1900
s
Click on picture for more information
Democritus(460 BC – 370 BC)
• Proposed an Atomic Theory (Atomos or Atomon) (along with his mentor Leucippus) which states: – all atoms are small, hard,
indivisible and indestructible particles made of a single material
– Can be rearranged to form different shapes and sizes.
• Aristotle did not support his atomic theory Image taken from:
https://reich-chemistry.wikispaces.com/T.+Glenn+Time+Line+Project
Antoine Lavoisier (1743 – 1794)
Known as the “Father of Modern Chemistry”
Was the first person to generate a list of thirty-three elements in his textbook
Discovered / proposed that combustion occurs when oxygen combines with other elements
Discovered / proposed the Law of Conservation of Mass (or Matter) which states, in a chemical reaction, matter is neither created nor destroyed
Devised the metric system Was married to a 13-year old Marie-
Anne Pierette Paulze; she assisted him with much of his work
Was a tax-collector that was consequently guillotined during the French Revolution
Image taken from: www.ldeo.columbia.edu/.../v1001/geotime2.html
John Dalton (1766 – 1844)
In 1803, proposed an Atomic Theory which states:o All substances are made of
atoms; atoms are small particles that cannot be created, divided, or destroyed.
o Atoms of the same element are exactly alike, and atoms of different elements are different
o Atoms join with other atoms to make new substances
Calculated the atomic weights of many various elements
Was a teacher at a very young age Was color blind Image taken from:
chemistry.about.com/.../John-Dalton.htm
J.J. Thomson (1856 – 1940)
Proved that an atom can be divided into smaller parts
While experimenting with cathode-ray tubes, discovered “corpuscles”, which were later called electrons
Stated that the atom is neutral In 1897, proposed the Plum
Pudding Model which states that atoms mostly consist of positively charged material with negatively charged particles (electrons) located throughout the positive material
Won a Nobel Prize, 1906
Image taken from: www.wired.com/.../news/2008/04/dayintech_0430
Ernest Rutherford (1871 – 1937)
In 1909, performed the Gold Foil Experiment and suggested the following characteristics of the atom:o An atom consists of a small core, or
nucleus, that contains most of the mass of the atom
o This nucleus is made up of particles called protons, which have a positive charge
o The protons are surrounded by negatively charged electrons, but most of the atom is actually empty space
o Rutherford’s model was called the “planetary model”
Did extensive work on radioactivity (alpha & beta particles, gamma rays/waves) and was referred to as the “Father of Nuclear Physics”
Won a Nobel Prize, 1908 Was a student of J.J. Thomson Was on the New Zealand $100 bill
Image taken from: http://www.scientific-web.com/en/Physics/Biographies/ErnestRutherford.html
Marie Curie Pioneered the science of
radiology & study of radioactive decay
Developed methods for the separation of radium from its ore
Promoted use of radium to alleviate soldier’s suffering
referred to as the “Mother of Modern Physics”
Won a Nobel Prize, 1903 Discovered the element
Polonium
Marie Curie(1867 – 1934)
Lise Meitner(1878– 1968)
Collaborated with Otto Hahn in the study of chemistry, Hahn won Nobel Prize for their work
Einstein referred to her as the “German Marie Curie”
In 1939, co-discovered (with Hahn) nuclear fission, proving the atom could be broken down into sub-atomic particles
Niels Bohr (1885 – 1962)
In 1913, proposed the Bohr Model, which suggests that: electrons travel around the
nucleus of an atom in orbits or definite paths.
electrons can jump from a path in one level to a path in another level (depending on their energy)
Won a Nobel Prize, 1922 Worked with Ernest Rutherford Image taken from:
commons.wikimedia.org/wiki/File:Niels_Bohr.jpg
Louis de Broglie(1892-1987)
• In 1924, presented research that led to the development the theory of Wave Mechanics also called Quantum Theory or Quantum Mechanics**
• transformed knowledge of physical phenomena on the atomic scale.
• Won Nobel Prize, 1929
Werner Heisenberg(1901-1976)
• Studied plasma physics, atomic physics and thermonuclear processes
• Won Nobel prize, 1932• Famous for Heisenberg
Uncertainty Principle – electrons do NOT travel in neat orbits
• 1925-Introduced Theory of Quantum Mechanics* to explain behaviors of electrons and other subatomic particles
Erwin Schrodinger (1887-1961)
• In 1926, he further explained the nature of electrons in an atom by stating that:– the exact location of an electron
cannot be stated; therefore, it is more accurate to view the electrons in regions called electron clouds; electron clouds are places where the electrons are likely to be found
• Did extensive work on the Wave formula Schrodinger equation
• Won a Nobel Prize, 1933
Image taken from: nobelprize.org/.../1933/schroding
er-bio.html
James Chadwick (1891 – 1974)
Realized that the atomic mass of most elements was double the number of protons discovery of the neutron in 1932
Worked on the Manhattan Project Worked with Ernest Rutherford Won a Nobel Prize, 1935
Image taken from: www.wired.com/.../news/2009/02/
dayintech_0227
Murray Gell-Mann(1929 – )
• Won the Nobel Prize, 1969
• In 1964 proposed that protons and neutrons were made up of sub-subatomic particles called “quarks”– Can never be isolated– There are up quarks
and down quarks
Progression of the Atomic Model
The structure of an atom, according to:
Democritus & John DaltonJ.J. ThomsonErnest RutherfordNeils BohrErwin SchrodingerJames Chadwick
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