Atomic Theory

1
Atomic Theory
2
Question of the Day

• What is energy?
• What is the relationship of Kinetic Molecular
  Theory and atoms?
• How does light express the atomic structure?

3
Before Atomic Theory
4

• James P. Joule
• 1818 - 1889
• Born to a brewery family in Salford, Lanchsire,
  England
• Studied at home and published many papers on heat
  transfer
• Became the head of the Joule Brewery
• Combined the effort many scientists to create
  Kinectic Theory

Wikipedia http//en.wikipedia.org/wikiJames_Presc
ott_Joule/
5
Energy

• First, What is Work?
• A force through the distance.
• W Fd
• Units of Work
• 1 unit of work 1 N 1m
• 1 kg m2/s2 1 Joule
• Power
• 1 unit of power 1 Work / time
• 1 Joule/ Second 1 Watt

6
Power

• Power is a unit of energy over time.
• Like water flowing out of a pipe.
• Power

7
Kinetic Energy
8
Potential Energy
9
Kinetic Energy of Car

• The car from last lecture is moving at 30 m/s.
  What is the kinetic energy of the car?

10
Kinetic Energy of a Plane

• The plane from the last lecture is going at 65
  m/s. What is the kinetic energy of the plane?

11
Potential Energy of a Car

• What is the potential energy of the above car
  when it is on a hill of 300 m?

12
Potential Energy of a Plane

• The above plane is traveling at an altitude of
  2,000 m above ground level. What is the potential
  energy of the plane?

13
Conservation of Energy

• Energy is never created or destroyed. Energy can
  be converted to one form to another but the total
  energy remains the same.
• Work against
• Inertia conserved
• Gravity conserved
• Friction not conserved, heat released
• Shape not conserved, heat transferred

14
Kinetic Molecular Theory

• Democritus (5th Century B.C.)
• Introduced atoms
• Rejected by Arstotle
• Elements represented by earth,wind,fire, and air
• Galileo and Newton suggested he might be right,
  but not confirmed
• Kinetic Molecular Theory

15
KMT (cont.)

• Molecules
• Made of atoms
• Compounds like H20
• Smallest compound components
• Diatomic O2
• Monatomic H
• Interactions
• Cohesion like atoms
• Adhesion unlike atoms

16
KMT (cont.)

• Phase of matter
• Solid Liquid Gas
• Solid
• Fixed Volume, Fixed Shape
• Can be pressurized
• Liquid
• Fixed Volume, Variable Shape
• Cant be pressurized
• Gas
• Variable Volume and shape
• Can be pressurized
• Vapor
• Plasma

17
KMT (cont.)

• Molecule motion
• Diffusion
• Average Kinetic Energy
• Temperature
• http//jersey.uoregon.edu/Balloon/index.html

18
Wavelengths and Frequencies
Wikimedia http//upload.wikimedia.org/wikipedia/c
ommons/e/e9/Wave.png
19
Wavelengths and Frequencies
20
Wavelength of Light

• If a frequency of a light wave is 1.205X1015 Hz
  (1/s), what is the wavelength of this light?

21
Wavelength of Light

• What is the wavelength of light that has the
  frequency of 7.947X1014 Hz? In which part of the
  electromagnetic spectrum is the wavelength?

22
Energy of Light

•  

23
Energy of Light

• What is the energy of light that has a frequency
  of 7.947X1014 Hz?

24
Electromagnetic Spectrum
http//www.falloutradiation.com/image.phpidReNpLt
DK2qs60MrCGYEMoNgLzawGCDQhZ.jpeg
25
Waves

• Diffraction
• Huygens
• Light bending around an opaque object
• Interference
• Youngs double slit experiment

26
Waves (cont.)

• Polarization
• Light is a transverse wave
• Plane-polarized light
• Types
• Selective Astronomy, Polaroid cameras
• Reflective Sun glasses
• Scattering IMAX

27
Diffraction
28
Particles

• Photoelectric effect
• A quanta - Photons
• Gravitational Lenses

29
Gravitational Lens
30
Present Theory

• Wave and Particle come together
• Wavicle
• Particle when acted upon by macro forces
• Wave when acted up by the micro forces

31
A Photon of Light
32
What is an Atom?

• First Definition Democritus
• Thought objects were made of smaller objects
• Elements (Robert Boyle)
• Pure substances, one could not purify any further
• John Daltons Experimentation
• Noticed how the 1 gram oxygen always combined
  with 13 grams Lead to create Lead Oxide
• If substances continuous, then they would combine
  in any mixture

33

• J.J. Thomson
• 1856 - 1940
• Born in Cheetham Hill, Manchester, England
• Studied and became Master of Trinity College,
  Cambridge
• Fathered two children
• Both he (1906) and his son (1937) won the Nobel
  Prize

Wikipedia http//en.wikipedia.org/wiki/J._J._Thom
son
34
J.J. Thomsons Experiments

• Thomson wanted to explore the conduction of
  cathode rays in cathode ray tubes
• He created electric field around the ray tube.
• He noted the charged particles flowed toward the
  positive terminal indicating they were negatively
  charged and named these particles electrons.
• Thomson suggested these particles were embedded
  in an ether like raisins in plum pudding.

35

• Robert A. Milikan
• 1868 -1953
• Studied at Columbia and went to work at
  University of Chicago
• Won the Nobel in 1923 for his work with electric
  properties of fluids
• Became one of the founders of the California
  Institute of Technology

Wikipedia http//en.wikipedia.org/wiki/Robert_And
rews_Millikan
36
Milikans Experiments

• Charged oil drops were deflected using charged
  plates
• Thomson had found a q/m, but Millikan used to
  gravity to confirm this result.
• Showed that charge was quantized.
• Masselectron 9.11 x 10-31 kg

37
Other Structures
Other Structures were suggested by the presence
of Alpha, Beta, and Gamma Rays
38

• Ernest Rutherford
• 1871 1937
• Studied in New Zealand and worked in Cavendish
  lab in Cambridge
• Won the Nobel Prize (1907) and was knighted in
  1914
• His students discovered the Ionsphere and
  developed the particle accelerator.

Wikipedia http//en.wikipedia.org/wiki/Ernest_Rut
herford
39
Rutherfords Experiments

• Focused a beam of alpha particles through a thin
  sheet of Au (Gold) then detected behind by zinc
  sulfide that sparked when alpha hit it.
• Most particles went through the sheet of Au, but
  some were back scattered by a small object,
  assumed to be a nucleus
• Regions assumed to be 10-13 to 10-8 cm
• massproton 1.67 X 10-27 kg

40
Rutherfords Experiment

• Used alpha to break up the nucleus of a N
  (nitrogen) atom and found 7 discrete unit of
  charge like the electrons, but positively charged
• Called the particles protons
• Lead to atomic number for each element
• Maxwell put the proton and electron together with
  the electron orbiting the proton

41

• Niels Bohr
• 1855 1962
• Studied at Copenhagen and then joined Rutherford
  and Thomson at Cambridge
• Returned to Copenhagen and then went to United
  States to work on the Manhattan Project
• Was a great footballer (soccer) player

Wikipedia http//en.wikipedia.org/wiki/Niels_Bohr
42
Bohrs Model of the Atom

•  

43
Spectra and Elements
http//jersey.uoregon.edu/elements/Elements.html
44
Spectral Wavelengths

•  

45
Spectral Wavelengths

• What level produces the frequency 7.947X1014 Hz?

46
Bohrs Model of the Atom

• Allowed orbits have angular momentum conserved
  and angular force corrected
• mvr nh/2?
• kq1q2/r2 mv2/r
• Solving the equations simultaneously we get the
  Bohr radius of 5.29 X 10-11 m

47
Bohrs model of the Atom

• Stable orbits do not give off radiation.
• Quantum leaps emit or absorb radiation.
• Bohr model worked wonderfully for H, but did not
  work for higher atoms so we needed a new science,
  Quantum Mechanics

48

• Erwin Schröndinger
• 1887 - 1961
• Studied in Austria and worked in Oxford, Ireland,
  and Austria
• Won the Nobel Prize (1933)
• His work with quantum mechanics inspired many to
  find similar structure in biological life, i.e.
  DNA

Wikipedia http//en.wikipedia.org/wiki/Erwin_Schr
C3B6dinger
49
Quantum Mechanics

• All particles, proton and electrons, are
  considered matter waves
• All matter waves have a range of positions and
  velocities and one must observe the particle to
  determine these values.
• Some values are incompatibly observed such are
  position and velocity or energy and time, i.e.
  the Heisenberg Uncertainty Principle.

50
Quantum Mechanics (cont.)

• Quantum Mechanics Model
• Fuzzy versus Strong
• Hiesenberg Uncertainty Principle
• Distance, orbital, orientation, and then
  direction
• Principle quantum number n 1,2,3
• Angular momentum l 0,1,(n-1)
• Magnetic quantum number ml -l1
• Spin number s -1/2,1/2
• Pauli Exclusion Principle

51
Electron Configuration
Energy Level Orbital Number of e- Number of e-/level
1 0,s 2 2
2 0,s 2
1,p 6 8
3 0,s 2
1,p 6
2,d 10 18
4 0,s 2
1,p 6
2,d 10
3,f 14 32
52
Electronic Orbitals
http//ahs.wcs.k12.va.us/Chem20Web20Final_files/
image012.jpg
53
After Atomic Theory

• Schrodinger's Cat

54
Homework 5

• Comment in three paragraphs comparing and
  contrasting the differences in dating advice
  before and after atomic theory in the Curves in
  the Path.. post. Use examples from the Richard
  Feynman reading in your response.
• List the parts of the electromagnetic spectrum
  and the everyday objects emit each part.
• What is the frequency of light that has a
  wavelength of 2.797X10-7m? What is the energy of
  this frequency of light? What electronic level
  transition occurs to produce this wavelength in
  the Balmer Series?