Atomic Structure- History Philosophers and Scientists Know how the following contributed to the...
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Transcript of Atomic Structure- History Philosophers and Scientists Know how the following contributed to the...
Atomic Structure- History
Philosophers and Scientists• Know how the following contributed to the history of
the atom:Philosophers from History of the Atom video– Empedicles - four “elements” – earth, water, fire, air.
– Leucippus - the first Greek to develop the theory of atomism — the idea that everything is composed entirely of various imperishable, indivisible elements called atoms
– Aristotle - five elements – earth, air, fire, water, and aether
Next week
Modern Day scientists– Dalton• atoms could not be divided• all elements of a given element are the same• different atoms could join to form compounds
– Thomson• the plum pudding model• negatively-charged "plums” surrounded by
positively-charged "pudding”– Rutherford http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/ruther14.swf
• atom is made up of a central charge surrounded by a cloud of orbiting electrons
– Bohr• electrons are in levels around the nucleus
Structure of the Atom
Particle Charge Mass
(atomic mass units)
Location
Proton positive
+
1 nucleus
Neutron neutral
Ø
1 nucleus
Electron negative
-
0.0006 orbit, level, cloud
The Nucleus
A 1946 test of an atomic bomb in the lagoon at Bikini atoll. The explosion has just started; surplus ships moored nearby can still be
seen.
http://video.google.com/videosearch?sourceid=navclient&rlz=1T4SUNA_enUS3
16US316&q=atomic%20bomb&um=1&hl=en&ie=UTF-
8&sa=N&tab=iv#
http://www.youtube.com/watch?v=bw85r24WW3s
• The nucleus– the center of the atom composed
of protons and neutrons– held together by four forces (electromagnetic,
strong , weak, and gravity)– 99.9% of the atom’s mass is here– about 100,000 times smaller than
the entire atom– the atomic number of an atom is the number
of protons in the nucleus– the atomic mass or mass number of an atom is
the sum of the protons and neutrons
– Isotopes• atoms with the same number of protons (and
therefore the same element) but with a different number of neutrons.