FNI 1H Quantum Mechanics 1 Quantum Mechanics. FNI 1H Quantum Mechanics2 Energy is the capacity to do work Kinetic Energy is energy of motion Potential

FNI 1H Quantum Mechanics 1

Quantum Mechanics


Energy is the capacity to do work

Kinetic Energy is energy of motionPotential Energy is stored energyHeat is the energy of random motion


Energy and Matter are related through Einstein’s famous equation:E=mc2

Matter is really just a very compact form of energy


Work and Kinetic Energyw = f d KE = ½ mv2 Work is defined as applying a force through

a distance. Energy is the capacity of a physical system

to do work. The units of energy are the Joule, J which is

the same as kg m2/s2 .

http://hyperphysics.phy-astr.gsu.edu/hbase/work.html#wep


Units of EnergyEnergy Units Definition Conversion factors

Joule, J Metric unit for energy 1 kg m2/s2

Electron Volt, eV

Energy of an electron accelerated by one volt of potential

1 eV = 1.602 x 10-19 J

calorie, cal

Calorie = kcal

The amount of heat energy needed to raise one gram of water 1º C.

4.184 J


Energy of a photon

E=hf

E is the energy of the photonf is the frequency of the photonh is Planck’s constant

h = 6.626068 x 10-34 m2kg/s


Calculate the frequency and energy of both a red (655 nm) and blue (350 nm) photon. Compare both the energy and frequency.

Wavelength Frequency Energy

655 nm

350 nm


Quantum Mechanics

Photoelectric effect Wave particle duality Characteristic energy Quantum numbers Electron spin Electron tunneling Uncertainty principle Quantum entanglement


Photoelectric Effect

It was found that when light shines on certain metals electrons are given off. Whether an electron is given off depends on the energy of the light. The energy of the electron given off depends on the energy of the light.

This experiment was used to show that light behaves like particles.

Solar cell demo Photovoltaic Photoresistor demo http://www.aip.org/history/einstein/essay-photoelectric.htm http://hyperphysics.phy-astr.gsu.edu/hbase/mod1.html#c2 http://www.solarserver.de/wissen/photovoltaik-e.html http://en.wikipedia.org/wiki/Photocell

View DVD “Power of the Sun” 15 minutes


Charge Q, Volts V, Electron volts eV, E = QV Charge usually has the symbol Q and the units

Coulombs, C.

6.242 x 1018 electrons together have a charge of 1 Coulomb.

1 e- = 1.602 x 10-19 C

A volt is electric potential energy. It is measured in J/C.

An electron volt is the energy an electron has when it is accelerated through one volt of electric potential.

1 eV = 1.602 x 10-19 J


KE = Eγ-w

Photoelectric effect

Potassium = 2.0 eV needed to eject electron

700 nm1.77 eV

550 nm2.25 eV

400 nm3.1 eV

Vmax = 6.22 x 105 m/s

Vmax = 2.96 x 105 m/s

Eγ = hf

e-e-

No electron


KE = Ephoton-w

KE = ½ mv2 h = 6.626x10-34 m2kg/s

me = 9.11x10-31 kg

c = 2.998x108 m/s

1 eV = 1.602x10-19 J

Eγ = hf

KE = Eγ – w

c = λf


Photoelectric Effect ExampleCalcium work function 2.9 eVGreen light 532 nm

Will electrons be produced if a green laser is directed onto calcium metal?

How fast will the electron be traveling?

http://hyperphysics.phy-astr.gsu.edu/hbase/tables/photoelec.html#c1

h = 6.626x10-34 m2kg/s

me = 9.11x10-31 kg

c = 2.998x108 m/s

1 eV = 1.602x10-19 J

Eγ = hf

KE = Eγ – w

c = λf


Photoelectric Effect PracticeSodium work function 2.28 eVRed light 655 nm

Will electrons be produced?

How fast will the electrons be traveling?

http://hyperphysics.phy-astr.gsu.edu/hbase/tables/photoelec.html#c1


Wave Particle Duality of Subatomic Particles

It turns out that matter can sometimes be modeled best as waves and sometimes best as particles.

For part 3 go to the following web site:http://www.colorado.edu/physics/2000/schroedinger/index.html






DeBroglie Wavelength hλ=

mvWhere:m is massv is velocity h is 6.626 x 10-34 m2kg/s (Planck’s Constant)


Characteristic Energy and Spectroscopy

When gasses are excited by an electric field they give off discrete light.

The spectrum of light given off is unique to each element.

This means that electrons can only have certain energy levels.

By treating electrons as standing waves theory can be made to match experimental results.

As energy levels increase more nodes are introduced to the three dimensional waves.


Electron Orbitalshttp://www.shef.ac.uk/chemistry/orbitron/

1s

2s 2p

Demos: Slinky, Flute and Gas Light, diffraction grating glasses


1s

2s

3s

2p

3p


How can we use light to find out about the nature of matter?

Spectroscopy


Applications of Spectroscopy UV-spectroscopy is used to detect optical endpoints in

plasma reactors. Since products in a chemical reaction give off a characteristic spectrum it can be used to determine when a reaction is complete.

UV-Vis Spectroscopy is used in many biological applications such as detection of DNA or proteins.

X-ray spectroscopy can be used with an electron microcope to determine which elements are present in a sample and in what proportions.

Infrared spectroscopy is used to analyze materials and determine their chemical structure.

Documents

FNI 1H Quantum Mechanics 1 Quantum Mechanics. FNI 1H Quantum Mechanics2 Energy is the capacity to do work Kinetic Energy is energy of motion Potential