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Electron Behavior Electron absorb energy and jump to higher energy level (Excited State). Immediately fall back to original level (Ground State) emitting the energy in the form of electromagnetic radiation. Energy is released in discrete packets called quanta. The process is referred to as a “quantum leap.”

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**Light and Atomic Spectra**

Every element emits light when its excited. Light quanta are called photons. Atomic Emission Spectra the light emitted by an electron and passed through a prism. Consists of a few lines are called line spectra. The emission spectrum of each element is unique to that element.

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**Energy Absorption and Emission**

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Photoelectric Effect Albert Einstein proposed that light could be described as quanta of energy that behaves like particles. Photoelectric effect – metals eject electrons when light shines on them. Only when the frequency of light is above the threshold frequency will the photoelectric effect occur. Practical use: solar panels, solar calculators

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**Electromagnetic Spectrum**

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**Electromagnetic Spectrum**

Radio Waves Microwaves Infrared Waves Visible Light Waves Ultraviolet Waves X-rays Gamma Rays Longest Wavelength/Lowest Frequency Shortest Wavelength/Highest Frequency

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**Visible Light Spectrum**

Memory device: ROY G. BIV red-orange-yellow-green-blue-indigo-violet Orders colors from lowest frequency/longest wavelength to highest frequency/shortest wavelength.

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Anatomy of a Wave Wavelength (λ): Distance between analogous parts of a wave. Crest: Top of wave Trough: Bottom of wave Amplitude: Height of wave (related to amount of energy a wave has) Resting Position

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Frequency Frequency (f): the number of wave cycles that pass in a given amount of time. If the time is 1 second the unit for frequency is Hertz (Hz, 1/s, s-1).

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**Frequency vs. Wavelength**

Frequency and wavelength have an inverse relationship. As frequency increases, the wavelength decreases. As frequency decreases, the wavelength increases.

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**Equations Wave Velocity/Speed**

This formula measures the velocity/speed of a wave. v = f x λ v = velocity f = frequency λ = wavelength Speed of light in a vacuum = 3.0 x 1010 cm/s or 3.0 x 108 m/s

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Practice A wave is traveling at a velocity of 12 m/s and its wavelength is 3m. Calculate wave frequency. Calculate the wavelength of yellow light emitted by a sodium lamp if the frequency of the radiation is 5.10 x 1014 Hz (5.1 x 1014 s-1). The speed of all light in a vacuum is 3.0 x 1010 cm/s. What frequency is radiation with a wavelength of 5.00 x 10-6 cm? The speed of all light in a vacuum is 3.0 x 1010 cm/s. In what region of the EM Spectrum is this radiation.

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**Equations h = 6.6262 x 10-34 J • s Planck’s Constant**

This formula measures energy of a quantum. E = h x f h = x J • s f = frequency E = amount of radiant energy absorbed or emitted.

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Practice Orange light has a frequency of 4.8x s -1. What is the energy of one quantum of orange light? The threshold photoelectric effect in tungsten is produced by light of wavelength 2.6 x 10-7 m. Give the energy of a photon of this light in joules (speed of light is 3.0 x 108 m/s).

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