4 } Bohr’s Model Further away from the nucleus means higher energy. There is no “in between” energyEnergy LevelsFifthFourthThirdIncreasing energySecondFirstNucleus
5 The Quantum Mechanical Model The atom is found inside a blurry “electron cloud”area where there is a chance of finding an electron.
6 Evidence of Quantum Mechanical Model The study of light led to the development of the quantum mechanical model.Light is a kind of electromagnetic radiation.Electromagnetic radiation includes many kinds of wavesAll move at 3.00 x 108 m/s ( c)
7 Parts of a waveCrestWavelengthAmplitudeOrginTrough
8 Parts of Wave Orgin - the base line of the energy. Crest - high point on a waveTrough - Low point on a waveAmplitude - distance from origin to crestWavelength - distance from crest to crestabbreviated l (Greek letter lambda).
9 FrequencyThe number of waves that pass a given point per second.Units are cycles/sec, or hertz (hz)Abbreviated n the Greek letter nuc = ln
10 Frequency and wavelength Are inversely relatedAs one goes up, the other goes down.Different frequencies of light are different colors of light.Wide variety of frequenciesThe whole range is called a spectrum
12 How color tells us about atoms Atomic SpectrumHow color tells us about atoms
13 PrismWhite light is made up of all the colors of the visible spectrum.Passing it through a prism separates it.
14 If the light is not white By heating a gas with electricity we can get it to give off colors.Passing this light through a prism does something different...
15 Atomic Spectrum Each element gives off its own characteristic colors. Can be used to identify the atom.Composition of stars.
16 Emission SpectraThese are called discontinuous spectra, or line spectraunique to each element.Light is given off, or emitted.
17 Energy and frequency (Honors) E = hnE is the energy of the photonn is the frequencyh is Planck’s constanth = x Joules sec.Joule is the metric unit of Energy
18 Equations for LightOnly 2 equationsc = lnE = hnPlug and chug.
19 ExamplesWhat is the wavelength of blue light with a frequency of 8.3 x 1015 hz?What is the frequency of red light with a wavelength of 4.2 x 10-5 m?What is the energy of a photon of each of the above?
27 UltravioletVisibleInfraredFurther they fall, more energy, higher frequency.This is simplifiedthe orbitals also have different energies inside energy levelsAll the electrons can move around.
28 Heisenberg Uncertainty Principle It is impossible to know exactly the speed and velocity of a particle.The better we know one, the less we know the other.The act of measuring changes the properties.
29 More obvious with the very small To measure where a electron is, we use light.But the light moves the electronAnd hitting the electron changes the frequency of the light.
30 After Before Photon changes wavelength Photon Moving Electron Electron Changes velocityMoving Electron