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Electromagnetic Radiation Definition: Characteristics of Waves Wavelength (λ): Frequency (v): Amplitude: Draw and Label the parts of a wave: Formulas to remember Electromagnetic wave relationship c = λ v Using Planck’s constant E quantum = hv Photoelectric Effect E photon = hv What do the variables stand for? Equantum (J)= ______________ Ephoton (J) = _______________ λ (m, cm, nm) = _____________ h (J∙s) = __________________ v ( Hz, s -1 )= ________________ c (m/s)= ___________________ h = 6.626 x 10 -34 J∙s J is joules and is the unit for energy c = 3.00 x 10 8 m/s Other relevant Info. White light can be separated into ____________________________ The color with the highest frequency is_______/ with the lowest frequency is _________ List the different forms of electromagnetic radiation in order of least to greatest frequency:____ ____________________ As photon energy increases, what happens to wavelength and frequency?___________ ____________________

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Name:__________ Date: _________ Period:_______ Practice Problems What is the wavelength of a microwave with a frequency of 5.22 x 10 8 Hz? Formula: Work: Ans with correct units and proper sig figs. Calculate the frequency of photon that has an energy of 5.313 x 10 -16 J What is the energy of a quantum with a frequency of 1.05 x 10 16 s -1 Formula: Work: Ans with correct units and proper sig figs. Formula: Work: Ans with correct units and proper sig figs.

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Chapter 5 in your text pp. 117-141

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In the early 1900’s scientist discovered that certain elements gave off visible light when heated in a flame. Analysis of this light revealed that an element’s chemical behavior is related to the arrangement of electrons. Because of this, it became important to understand nature of light

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Electromagnetic radiation: a form of energy that exhibits wavelike behavior as it travels through space. Examples Visible light from the sun, microwaves, x-rays, radio waves, etc

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Wavelength: λ shortest distance between equivalent points on a continuous wave; measured from crest to crest or trough to trough expressed in meters, centimeters, or nanometers Frequency: v The number of waves that pass a given point per second Expressed in hertz (Hz or s -1 ) Amplitude Wave’s height from the origin to a crest or origin to a trough crest amplitud e origin

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c = λ v where c is the speed of light, λ is wavelength, and v is frequency Example: What is the wavelength of a microwave with a frequency of 3.44 x 10 9 Hz? λ = c/v λ = 3.00 x 10 8 m/s = 8.72 x 10 -2 m 3.44 x 10 s -1

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Although the speed of Electromagnetic waves is the same, wavelengths and frequencies can be different (ex: higher frequency = shorter wavelength) White light, such as sunlight, can be separated into a continuous spectrum of colors if passed through a prism. These are the colors of the rainbow (roy g biv – red, orange, yellow, green, blue, indigo, violet)

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Electromagnetic spectrum (EM spectrum) is all forms of electromagnetic radiation where the only difference in the types of radiation is their wavelengths and frequencies

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The wave model couldn’t explain the emission of the different wavelengths. In 1900, Max Planck studied the light given off by heated objects. His studies led him to the conclusion that matter can gain or lose energy in small amounts called “quanta.” A Quantum is the minimum amount of energy that can be gained/lost by an atom

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E quantum = hv E quantum is energy, h is Planck’s constant, and v is frequency The value for Planck’s constant is 6.626 x 10 -34 J∙s J is joules and is the unit for energy Example: What is the energy of a photon from the violet portion of the Sun’s light if it has a frequency of 7.230 x 10 14 s -1 ? Ephoton = (6.626 x 10 -34 J∙s) (7.230 x 10 14 s -1 ) = 4.791 x 10 -18 J

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Photoelectrons are given off a metal’s surface when light of a certain frequency shines on the surface Einstein proposed light has a dual nature- A beam of light has wavelike and particlelike properties. A beam of bundles of energy were called photons (massless particle that carries a quantum of energy. E photon = hv As the energy of a photon increases, the frequency increases. What can you conclude about the wavelength.

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