Ch07 MSJ jlm

Ch07 MSJ jlm - Chapter 7 Electronic Configurations and Electronic the Periodic Table the Robert W Bunsen 1811-1899 Established the science of

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1 Electronic Configurations and Electronic Configurations and the Periodic Table the Periodic Table Chapter 7 Chapter 7 Robert W. Bunsen 1811-1899. Established the science of spectroscopy. Niels H. Bohr 1885-1962.* Related Periodic Table to atomic atomic structure and spectral behavior.

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2 The Wave Nature of Light The Wave Nature of Light Modern atomic theory arose out of studies of the interaction of radiation with matter. Electromagnetic radiation moves through a vacuum with a speed of 2.99792458 × 10 8 m/s. (We will usually round off to 3 x 10 8 m/s) Electromagnetic waves have characteristic wavelengths ( λ29 and frequencies ( ν ) . Example: visible radiation has wavelengths between λ = 400 nm (violet) and 750 nm (red).
3 The Wave Nature of Light The Wave Nature of Light Some examples of EM radiation: visible light ultraviolet radiation (UV) infrared radiation (IR) radio waves microwaves x-rays ?sound waves?

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4 The Wave Nature of Light The Wave Nature of Light The frequency , ν , of a wave is the number of cycles which pass a point in one second. The speed of a wave, c , is given by its frequency multiplied by its wavelength: c = ν λ where c = 3 x 10 8 m.s -1 (the “speed of light”) The wavelength, λ, is the distance between crests in a wave
5 Short wavelength High frequency as λ ν Long wavelength Small frequency as λ ν

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6 The Wave Nature of Light The Wave Nature of Light
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8 Quantized Energy and Photons Quantized Energy and Photons Some problems affecting science in 1900 : Blackbody radiation Blackbody radiation Photoelectric effect Photoelectric effect Line spectra Line spectra Spiraling of electrons into nucleus Spiraling of electrons into nucleus
9 Quantized Energy and Photons Quantized Energy and Photons Planck Planck: energy can only be absorbed or released from atoms in certain amounts called quanta quanta . This energy is proportional to the frequency ,R, of the radiation. The proportionality constant, h, is called Planck ’s constant and is equal to: 6.626 × 10 -34 J.s E = hR Matter can absorb or emit energy only in quantum units which are multiples of hR : ΔE = nhR where n=integer

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10 Quantized Energy and Photons Quantized Energy and Photons The Photoelectric Effect The Photoelectric Effect The photoelectric effect provides evidence for the particle nature of light -- “quantization”. If light shines on the surface of a metal, there is a point at which electrons are ejected from the metal. The electrons will only be ejected once the threshold frequency , υ, is reached. Below the threshold frequency, no electrons are ejected. This is consistent with the Planck statement that light energy depends only on frequency.
11 Quantized Energy and Photons Quantized Energy and Photons The Photoelectric Effect The Photoelectric Effect

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12 Energy of ejected electrons threshold frequency ν o frequency, ν The Photoelectric Effect The Photoelectric Effect Einstein assumed that light traveled in energy packets called photons .
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This note was uploaded on 04/12/2011 for the course CHEM 1420 taught by Professor Acree during the Spring '08 term at North Texas.

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Ch07 MSJ jlm - Chapter 7 Electronic Configurations and Electronic the Periodic Table the Robert W Bunsen 1811-1899 Established the science of

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