Bohrs Energy Levels Electrons in certain energy levels Orbits with certain amounts of energy Low energy levels closer to nucleus High energy levels farther from nucleus Ground state ID: 441430
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Slide1
Niels
Bohr’s Energy Levels
Electrons in certain energy levelsOrbits with certain amounts of energyLow energy levels: closer to nucleusHigh energy levels: farther from nucleusGround stateElectrons in lowest energy level possibleAufbau principleElectrons will occupy the lowest available energy level
Episode 303Slide2
Excited Atom
Atom has absorbed energy
Quanta – Energy required to excite an electronExcited state is unstableAtom soon emits same amount of absorbed energyEnergy seen as visible lightPhoton – particle with no mass containing a quanta of energyCOLOREpisode 303Slide3
Wave Description of Light
Wavelength (
λ)Distance between corresponding points on adjacent wavesFrequency(f or γ)The number of waves passing a given point in a given timeHertzC = λf
C =
3.0 x 10
8
m/s
: speed of
light
Episode 303Slide4
Electromagnetic Spectrum
What is the frequency of light if the wavelength is 6.0 x 10-7
m?C = λfC = 3.0 x 108 m/s : speed of light3.0 x 108 m/s = (6.0 x10-7 m) f
3.0 x 10
8
m/s
6.0 x10
-7
m
= f
5.0 x 10
14
/s = f
Episode 303
http://education.jlab.org/frost/speed_of_light.htmlSlide5
Electromagnetic Spectrum
What is the wavelength of light
if its frequency is 5.0 x 1014 Hertz?C = λfC = 3.0 x 108 m/s : speed of light3.0 x 108 m/s =
λ
(5.0 x 10
14
/s)
3.0 x 10
8
m/s
5.0 x 10
14
/s
=
λ
6.0 x 10
-7
m =
λ
Episode 303Slide6
Particle Description of Light
Energy exists as
particles called quantaPhotoelectric EffectMetal emits electrons when light strikes the metalE =hfh is Plank’s Constant6.626 x 10-34 JsEpisode 303Slide7
Electromagnetic Spectrum
How much energy does light contain if its frequency is 5.0 x 10
14 Hertz?E = hfh = 6.626 x 10-34 Js : Plank’s ConstantE= (6.626 x 10-34Js)(5.0 x 1014/s)
E = 3.3 x 10
-19
J
Episode 303Slide8
The Modern View of Light
Light has a
dual natureLight may behave as a waveLight may behave as a stream of particles called quanta or photonsEpisode 303Slide9
Spectroscopy
Spectral lines represent
energy released as electrons return to lower energy levelsSpectral lines identify an elementCalled the Bright Line Spectrum of an ElementEpisode 303Slide10
Orbital
Region of
space where an electron is likely to be foundHeisenberg Uncertainty PrincipleImpossible to determine location and velocity of a particle
Episode 303
http://www.youtube.com/watch?v=rNM21emkMJo&feature=related