1. Answers for Ch. 5 A + B (Part I)
Part A 4 3 1 2
Part B
12) 3.2 m
13) 23 m/s
14) 300 m/s
15) 12.7 m/s
16) m
17) 14.3 m
18) There was a decrease in flight time, a 45° always produces the greatest range
19) 34.6 m/s
20)
Horizontal Speed
Time

2. Regents Physics Mr. Rockensies
Modern Physics
Regents Physics
Mr. Rockensies

3. Quantum Theory
What is Quantum Theory?

4. Proposed by Max Planck in 1900.
States: “atoms absorb or emit light in
discrete amounts called Quanta or Photons.”
3) Photon – a “particle” of light carrying
energy & momentum.
Energy: Ephoton = h f or Ephoton = h c λ
Ephoton = energy of a photon λ = wavelength
h = Planck’s constant c = speed of light in a vacuum
f = frequency of light = 3.0 x 108 m/s

5. Photon – Particle Collisions (collision between photon & electron)
Photon energy and momentum decreases
Particle energy and momentum increases
Energy and momentum are conserved

6. Matter Waves
proposed by deBroglie in 1924
moving particles have wave properties only when particles are on a subatomic scale (electrons, protons, neutrons)
λ = h p
λ = wavelength of subatomic particle
h = Planck’s constant
p = momentum of subatomic particle
Example: What is the matter wavelength of an electron with a speed of 2.0 x 106 m/s?
λ = h p
λ = x J·s
(2.0 x 106 m/s)(9.1 x kg)
λ = 3.6 x m

7. How did the structure of the atom evolve?
Models of the atom
How did the structure of the atom evolve?

8. Rutherford’s Model Experiment (1911)
The detecting screen was illuminated with a flash of light every time an alpha particle hit it.

9. Rutherford’s Conclusions
1 % of alpha particles deflected into hyperbolic paths
99% of alpha particles passed through foil
most of the atom is empty space
positive charge and mass of atom is concentrated in a small dense core called the nucleus.
Rutherford’s atom

10. Bohr’s Model (1913) Bohr’s Model of the Atom
Bohr’s model agreed with what Rutherford had said two years previously, but added on certain distinctions
electrons move in orbits, shells, or energy levels around the nucleus and can move from one energy level to another.
Energy Level Diagrams
each atom of a particular element
has what is called an energy level
diagram
shows the energy levels or states
of an atom
Bohr’s Model of the Atom

11. Energy Level Diagrams Ground State
electron is in its lowest energy level
atom is most stable
electron has least amount of energy
Excited State
electron jumps to a higher energy level
atom is less stable
electron has more energy
Ionization Level
atom is “ionized” when electron is removed from atom
Ionization energy – energy needed to remove an electron from atom
** Signs indicate the energy the atom lacks to become ionized when in that state

12. Results of Absorption/Emission
atoms absorb energy by absorbing energy of both colliding:
electrons (electrical energy)
photons (light energy)
atoms release energy in the form of photons (light)
Absorption/Emission Spectrum

13. How do we predict the colors an element will give off?
On the reference table: Ephoton (electron) = Ei - Ef
Ephoton (electron) = energy of photon absorbed or released by atom OR
energy of electron absorbed by atom
Ei = initial energy of electron in the atom
Ef = final energy of electron in the atom
If we know the energy of the photon, we can then use E = hf to find the frequency of that photon.
If we know the frequency, then we can use our reference tables to look up the corresponding color.
We could also calculate wavelength using c = fλ

14. What color is the photon?
An electron is excited to the 3rd energy level, n=3, and then drops back down to n=2. How much energy is given off by the atom when the electron falls down?
What is the frequency of the photon being emitted?
What is the wavelength of that photon?
What is the color of that photon?
Ephoton = Ei – Ef
Ephoton = eV – (-3.40 eV)
Ephoton = 1.89 eV (must convert to J)
Ephoton = hf
3.02x10-19 J =(6.63x10-34 J•s)f
f = 4.56x1014 Hz
c = fλ
3x108 m/s =(4.56x1014 Hz)λ
λ = 6.58x10-7 m
Color on reference table: Red
1 eV = 1.6x10-19J

15. Cloud Model
States that there is no specific orbit for an electron as it moves about the nucleus. Instead, there is a region of most probable electron location called an electron cloud.

16. Emission/Bright line Spectrum
Atomic Spectra
Emission/Bright line Spectrum

17. How do we see the emission/bright line spectrum?
Spectroscope
(contains a prism)
colored light is passed through
Emission Spectrum for Xenon
gas discharge tube with Xenon gas

18. Emission Spectrum Absorption Spectrum Absorption/Emission Spectrum
A series of bright lines of color on a black background
Unique for each element (can be used to identify an element)
Each line of color corresponds to an energy level change for an electron and a wavelength emitted by the material
Absorption Spectrum
A series of dark lines on a bright background
A characteristic set of light wavelengths absorbed by a material
Absorption/Emission Spectrum

20. Einstein’s Mass-Energy Relationships

21. What is Einstein’s Theory of Relativity?
A mass, m, is equivalent to an amount of energy, E
As an equation – E = mc2
Where: E = Energy equivalent in Joules
m = mass of 1 atomic mass unit (a.m.u.) in kg
**1 a.m.u. = 1.66x10-27 kg**
c = speed of light in air/vacuum
This equation eventually led to the creation of this
(nuke)

22. What is the Energy Equivalent of 1 a.m.u. (Proton or Neutron)?
E = mc2
E = (1.66x10-27 kg)(3.0x108 m/s)2
E = 1.49x10-10 Joules
E = 9.31x108 eV = 931MeV
million electron-volts
1 a.m.u. = 9.31x108 or 931 MeV
**Conversion factor on Reference Table**

23. Example #1
Approximately how much energy in MeV’s is produced when 0.50 universal mass units of matter is completely converted into energy?

24. Example #2
100 MeV of energy is released by an atom during fission. What amount of mass in universal mass units is converted to energy?

25. Example #3
How much energy in Joules would be produced if 1.0x1013 kg of matter was entirely converted to energy?

26. Example #4
The average high school student has a mass of 60 kg. What is the energy equivalent in Joules and MeV’s?

27. Example #5
Calculate the maximum total mass, in kilograms, of a particle that could be created in the head on collision of a proton and an anti-proton, each having an energy of 1.6x10-7 Joule.

28. Fundamental Forces
What are the four fundamental forces in order from strongest to weakest?

29. Strong Force
Nuclear Force which holds a nucleus of an atom together against the enormous forces of repulsion of the protons
Short Ranged – range is meters (diameter of a medium sized nucleus

30. Electromagnetic Force
Manifests itself through the forces between charges and the magnetic force
Can be attractive or repulsive
Long Ranged – range is infinite

31. Weak Force Involved in many decays of nuclear particles
Responsible for the fusion of the Sun and the conversion of neutrons to protons in the nuclei
Short Ranged – range is meters

32. Gravity
A purely attractive force which acts along the line joining the centers of mass of the two masses
The forces on the 2 masses are equal in size, but opposite in direction, obeying Newton’s 3rd Law
Long Ranged – range is infinite

33. Classification of Matter
How is all matter classified?

34. The Standard Model All Matter Hadrons (Heavy) Leptons (Light)
Baryons(Very Heavy)
Mesons (Medium Heavy)
Made of 1 quark and 1 anti-quark
Made of 3 quarks

35. There are a total of 6 quarks (flavors)
-up, down, charm, strange, top, bottom
There are also 6 anti-quarks
There are also 6 Leptons
- electron, electron-neutrino, muon, muon-neutrino, tau, tau-neutrino
There are also 6 anti-Leptons

36. Bosons – The Four Fundamental Force Carriers
Strong Force gluon g
Weak Force W boson
Electric Force photon γ
Gravity Force graviton G
-Never detected

37. Common Baryons Proton p uud Anti-proton p ūūd Neutron n udd
Omega Ω sss

38. Common Mesons
Pion π+ ud
Anti-pion π- ūd
Kaon k- sū

39. Conservation Laws still apply
Mass/Energy - the total amount of mass and energy equivalent of mass (E=mc2) is constant
Momentum
Charge
Quantization of Charge (quarks)