4} Bohr’s Model Further away from the nucleus means higher energy. There is no “in between” energyEnergy LevelsFifthFourthThirdIncreasing energySecondFirstNucleus
5The Quantum Mechanical Model The atom is found inside a blurry “electron cloud”area where there is a chance of finding an electron.
6Evidence 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)
7Parts of a waveCrestWavelengthAmplitudeOrginTrough
8Parts 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).
9FrequencyThe number of waves that pass a given point per second.Units are cycles/sec, or hertz (hz)Abbreviated n the Greek letter nuc = ln
10Frequency 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
12How color tells us about atoms Atomic SpectrumHow color tells us about atoms
13PrismWhite light is made up of all the colors of the visible spectrum.Passing it through a prism separates it.
14If 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...
15Atomic Spectrum Each element gives off its own characteristic colors. Can be used to identify the atom.Composition of stars.
16Emission SpectraThese are called discontinuous spectra, or line spectraunique to each element.Light is given off, or emitted.
17Energy 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
18Equations for LightOnly 2 equationsc = lnE = hnPlug and chug.
19ExamplesWhat 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?