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electronic structure : the arrangement of electrons in an atom

?. AP Chemistry. Electronic Structure of Atoms. electronic structure : the arrangement of electrons in an atom. quantum mechanics : the physics that correctly describes atoms. E. B. electromagnetic radiation (i.e., light). -- . waves of oscillating electric (E)

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electronic structure : the arrangement of electrons in an atom

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  1. ? AP Chemistry Electronic Structure of Atoms electronic structure: the arrangement of electrons in an atom quantum mechanics: the physics that correctly describes atoms

  2. E B electromagnetic radiation (i.e., light) -- waves of oscillating electric (E) and magnetic (B) fields -- source is… vibrating electric charges

  3. Characteristics of a Wave crest amplitude A trough wavelengthl frequency: the number of cycles per unit time (usually sec) -- unit is Hz, or s–1

  4. ROYGBV electromagnetic spectrum: contains all of the “types” of light that vary according to frequency and wavelength IR UV visible X-rays microwaves radio waves cosmic rays gamma rays 750 nm 400 nm large l small l -- visible spectrum ranges from only ~400 to 750 nm (a very narrow band of spectrum) low f high f low energy high energy

  5. Albert Michelson (1879) -- first to get an accurate value for speed of light Albert Michelson (1852–1931) The speed of light in a vacuum (and in air) is constant: c = 3.00 x 108 m/s c = n l = f l -- Equation:

  6. In 1900, Max Planck assumed that energy can be absorbed or released only in certain discrete amounts, which he called quanta. Later, Albert Einstein dubbed a light “particle” that carried a quantum of energy a photon. Max Planck (1858–1947) E = h n = h f -- Equation: E = energy, in J h = Planck’s constant Albert Einstein = 6.63 x 10–34 J-s (i.e., J/Hz) (1879–1955)

  7. A radio station transmits at 95.5 MHz (FM 95.5). Calculate the wavelength of this light and the energy of one of its photons. 3.00 x 108 m/s c = f l = 3.14 m = 95.5 x 106 Hz E = h f = 6.63 x 10–34 J/Hz (95.5 x 106 Hz) = 6.33 x 10–26 J

  8. e– e– light source e– e– e– e– e– e– e– e– e– e– e– e– e– e– e– metal surface In 1905, Einstein explained the photoelectric effect using Planck’s quantum idea. -- only light at or above a threshold freq. will cause e– to be ejected from a metal surface ROYGBV Frequency (i.e., energy) of light determines IF e– are ejected or not, and with what KE. Intensity/brightness of light determines HOW MANY e– are ejected.

  9. ? Einstein also expanded Planck’s idea, saying that energy exists only in quanta. Light has both wavelike and particle-like qualities, and... so does matter.

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