Chapter 21 Atomic Physics – Flashcards

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What is blackbody radiation?
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electromagnetic waves reflected off a blackbody
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What is a blackbody?
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object that has absorbed almost all electromagnetic waves
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What is an example of a blackbody?
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black hole
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What is ultraviolet catastrophe?
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failed prediction of classical physics that the energy radiated by a blackbody at extremely short wavelengths is extremely large and that the total energy radiated is infinite; occurs in end of UV spectrum
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Gamma rays act more like
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particles
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Radio waves act more like
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transverse waves
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What is Compton shift?
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increase in the wavelength of a photon emitted relative to the photon absorbed when scattered by individual electrons or nucleons
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What is the photoelectric effect?
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emission of electrons from a material when light of certain frequencies shines on the surface of the material
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What is a photon?
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unit or quantum of light; a particle of electromagnetic radiation that has zero rest mass and carries a quantum of energy
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What is work function?
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minimum energy needed to remove an electron from a metal atom
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What is the emission spectrum?
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increase in the wavelength of a photon emitted relative to the photon absorbed when scattered by individual electrons or nucleons
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What is absorption spectrum?
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diagram or graph that indicates the wavelengths of radiant energy that a substance absorbs
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What is the uncertainty principle?
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principle that states that determining both the position and the velocity of an electron or any other particle simultaneously is impossible
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Red light has
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lower frequency, fatter wavelength
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Violet light has
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higher frequency, shorter wavelength
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What is the reasoning behind ultraviolet radiation?
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Max Planck said that this is because light is quantized
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Higher temperature =
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higher energy EM wave emitted
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What did ultraviolet catastrophe experiments show?
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Experiments showed that as the wavelength decreased, the energy decreased also
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What is quantized energy?
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submicroscopic electric oscillators called resonators could only absorb and give off certain amounts of energy
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What does quantized mean?
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bundles of energy (photons)
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greater the frequency of light =
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greater the KE of the electrons ejected
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higher frequency EM waves tend to act more like =
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particles
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Louis deBroglie proposed that
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all matter, not just light, behaved as both waves and particles
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Explain the Uncertainty Principle.
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to view an electron's location you would have to use light to see it. The light striking the electron would increase its energy, therefore changing its momentum
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What is the electron cloud?
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area in which you can predict that you can there will be an electron in there
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What does the fact that an emission spectrum contains only certain wavelengths show about electrons?
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Their energy is quantized
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The principal quantum number represented by _____
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n
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The spectrum of an incandescent solid is typically
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a continuous band of colors
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What information can an emission spectrum reveal about the elements present in a sample?
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both their identities and relative concentrations
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massive, positively charged particles that move at high speeds when emitted from radioactive materials
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alpha particles
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the lowest energy state occupied by an electron
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ground state
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the quantized features found inside an atom
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energy levels
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the set of wavelengths absorbed by a gas
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absorption spectrum
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the state of an atom that has absorbed energy
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excited state
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Who discovered that electrons are quantized?
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Plank
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Increasing intensity at threshold frequency
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EJECTS MORE ELECTRONS BUT DOES NOT INCREASE KE
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If a photon ejects a blue light and a new, higher energy photon ejects a light ... what is the color? red? purple?
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purple bc less frequency, higher energy
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What did Rutherford discover?
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the center of an atom's nucleus is positive
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What do emission and absorption show and where does it occur?
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only in visible light? show colors reflected or absorbed with white light
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What did Bohr discover?
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Hydrogen atom and that electrons have different energy levels
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What did DeBroglie's wavelength show?
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all particles vibrate
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Why can we not know the speed and location of an electron at the same time?
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time goes on and light makes the object move
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What ideas led to the Electron Cloud?
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Bohr, deBroglie's wavelength, and Uncertainty Principle
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What did Schrödinger say?
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we don't know what will happen until it happens, we also don't know the effects until they occur
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