Transcript Atomic structure - Mrs. Wernau's Pre-AP Chemistry

S.MORRIS 2006
Timeline of Atomic Theory
450 BC
1800’s
________________________________________________________
_
Democritus:
http://greatphilosophers.suite101.com/article.cfm/democritus_and_at
omistic_philosophy
http://www.fortbend.k12.tx.us/campuses/documents/Teach
er/2009/teacher_20090928_0656.doc
matter was made of
“atoms”
Dalton:
http://www.iun.edu/~cpanhd/C101webnotes/co
mposition/dalton.html
http://www.fortbend.k12.tx.us/campuses/docu
ments/Teacher/2009/teacher_20090928_0656_
2.doc
proposed 4
components to an
Atomic Theory.
Atomic Theory 1897-1920
___________________________________
Thomson
Planck
http://highered.mcgrawhill.com/sites/0072512644/student_vi
ew0/chapter2/animations_center.htm
l
http://web2.uwindsor.ca/c
ourses/physics/high_sch
ools/2005/Photoelectric_e
ffect/planck.html
negative
charge in the
atom 1897
Quanta
1901
Millikan
http://highered.mcgrawhill.com/sites/0072512644/stude
nt_view0/chapter2/animations_c
enter.html
charge on e1910
Rutherford
http://www.mhhe.com/phys
sci/chemistry/essentialche
mistry/flash/ruther14.swf
nucleus
1911
Bohr
http://www.wwnorton.com/college/ch
emistry/gilbert/tutorials/ch3.htm#top
http://www.chempractice.com/drills/j
ava_Bohr.php
quantum
model 1913
Contributions to Modern Atomic
Theory
De Broglie
Wave
Gell-Mann
nature of
Heisenberg
Quarks
matter
___________________________________
e- is a wave
1962
and a particle
1924
__
1926
Schrodinger
Chadwick
e- orbits as a
neutron
wave 1926
1932
HISTORY OF THE ATOM
460 BC
Democritus develops the idea of atoms
he pounded up materials in his pestle and
mortar until he had reduced them to smaller
and smaller particles which he called
ATOMA
(greek for indivisible)
HISTORY OF THE ATOM
1808
John Dalton
suggested that all matter was made up of
tiny spheres that were able to bounce around
with perfect elasticity and called them
ATOMS
Dalton’s Atomic Theory
• All matter consists of tiny particles.
• Atoms are indestructible and unchangeable
(Has been modified with recent discoveries
in nuclear chemistry)
• Elements are characterized by the mass of
their atoms.
• When elements react, their atoms combine in
simple, whole-number ratios. Their atoms
sometimes combine in more than one simple
Laws that came from Dalton’s
Atomic Theory
• Law of Conservation of Mass (mass
cannot be created or destroyed)
• Law of Definite Composition/ Law of
Proportions
• Law of Multiple Proportions
HISTORY OF THE ATOM
1898
Joseph John Thompson
found that atoms could sometimes eject a far
smaller negative particle which he called an
ELECTRON
HISTORY OF THE ATOM
1904
Thomson develops the idea that an atom was made up of
electrons scattered unevenly within an elastic sphere surrounded
by a soup of positive charge to balance the electron's charge
like plums surrounded by pudding.
PLUM PUDDING
MODEL
Thomson’s Experiment with the
Cathode Ray Tube
http://highered.mcgrawhill.com/sites/0072512644/student_view0/c
hapter2/animations_center.html#
Planck and the Quanta
• Click to read about Planck and his
experiments and ideas
• http://web2.uwindsor.ca/courses/physics/hi
gh_schools/2005/Photoelectric_effect/plan
ck.html
Millikan 1910
• http://highered.mcgrawhill.com/sites/0072512644/student_view
0/chapter2/animations_center.html
• Charge on an electron
HISTORY OF THE ATOM
1910
Ernest Rutherford: The Gold
Foil Experiment
oversaw Geiger and Marsden carrying out his
famous experiment.
they fired Helium nuclei at a piece of gold foil
which was only a few atoms thick.
they found that although most of them
passed through. About 1 in 10,000 hit
HISTORY OF THE ATOM
gold foil
helium nuclei
helium nuclei
They found that while most of the helium nuclei passed
through the foil, a small number were deflected and, to their
surprise, some helium nuclei bounced straight back. This
indicated a small dense positively charged center.
HISTORY OF THE ATOM
Rutherford’s new evidence allowed him to propose a more
detailed model with a central nucleus.
He suggested that the positive charge was all in a central
nucleus. With this holding the electrons in place by electrical
attraction. The electrons occupied most of the space of an
atom/ makes up most of the volume of an atom.
However, this was not the end of the story.
HISTORY OF THE ATOM
1913
Niels Bohr
studied under Rutherford at the Victoria
University in Manchester.
Bohr refined Rutherford's idea by adding
that the electrons were in orbits. Rather
like planets orbiting the sun. With each
orbit only able to contain a set number of
electrons.
Bohr’s Atom
electrons in orbits
nucleus
HELIUM ATOM
Shell
proton
+
-
N
N
+
electron
What do these particles consist of?
-
neutron
More Practice with Bohr Model
http://www.chempractice.com/drills/java
_Bohr.php
Parts of the atom
Particles of the Atom to date:
• Nucleus
– Protons = p+ = 3 quarks
Held together by
0
– Neutrons= n = 3 quarks
a force called :
Gluon
• Electron Cloud
– Electrons =e- (particle/wave)
Types of Quarks Determine Charge
http://nobelprize.org/educational_games/physics/matter/1.html
Quarks = up (+2/3) and down (-1/3)
p+ = 2ups and 1 down
up
+2 +2 -1 = +1
3
3 3
n0 = 2 down and 1
-1
3
-1
3
+2 = 0
3
Gluon forces
between
quarks
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