Transcript Atomic_Theory1

Atomic Theory
History of the Discoveries Related to the Atom
Timeline of Atomic Theory
450 BC
1800’s
_________________________________________________________
Democritus:
http://www.fortbend.k12.tx.us/campuses/documents/
Teacher/2008/teacher_20081003_1616.doc
matter was made of
“atoms”
Dalton:
http://www.iun.edu/~cpanhd/C101webnotes/co
mposition/dalton.html
proposed 5
components to an
Atomic Theory.
Dalton’s Theory: Foundation of
Future Investigations
• 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,
whole-number ratio.
http://web.visionlearning.com/dalton_playhouse/ad_loader.ht
ml
Click the link at home to
explore more about
experiments related to
Dalton’s 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
3 Basic 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
+2
3
+2
3
-1 =
3
+1
n0 = 2 down and 1 up
-1
3
-1
3
+2 = 0
3
Gluon forces
between
quarks
Predicting the Location of an
Electron in an Atom:
• Bohr proposed 4 characteristics to consider
to predict the location of an electron.
– l = the distance from the nucleus
– m = the shape of the orbital in which the eoccupies. (s,p,d,f)
– n = axis the orbital occupies. (x, y, z)
– s =spin of the e- (+1/2 , -1/2)
Distance from the nucleus:
• Levels 1-7: When looking at the periodic
table, can be determined by the period
Elementary Connections
number.
1
2
3
4
5
6
7
Shape of the Orbital on the
x,y,z Axis
• The number of electrons in a particular
region determines the shape.
s shape 2e-
p shape 6e-
Shape of the Orbital on the
x,y,z Axis
d shape 10e-
f shape 14e-
Atom with overlapping orbitals
Spin of the Electron
• http://www.colorado.edu/physics/2000/applets/a2.html
Do Electrons behave as a
particle or as wave?
Definition of Light:
– http://chemmovies.unl.edu/C
hemAnime/DEFLITD/DEFLIT
D.html
Einstein vs Bohr
Einstein: causality
If you know all the
initial conditions of
your system and you
know the laws of
physics, you can figure
out exactly what’s
going to happen
Bohr: Predictability
If you know
the initial
conditions and
you know the
laws of
physics, you
can figure out
the probability
of various
outcomes
happening, but
you can never
know which
one will
definitely
occur until
after it’s over.
Electrons travel in waves
Electron behavior as it moves
to other energy levels.
• This emitted energy
is equal to the
difference between
the high and low
energy levels, and
may be seen as
light.
Light emission tutorial
http://www2.wwnorton.com/college/chemistry/gilbert/tut
orials/ch3.htm
Electrons are Particles / Photons
• Electrons travel in discreet packets called
photons.
• To describe these unique packets or quantities
of energy the term “quanta” is used.
• Every element on the periodic table is made up
of atoms with a unique signature of spectral
lines
Electrons exhibit particle and
wave like behavior
“Duality”