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62 Cards in this Set
- Front
- Back
What is the key feature of the quantum theory?
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Observable outcomes are unpredictable even when the outcomes arise from identical starting conditions. "quantum uncertainty."
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What equation of the overall statistics of large numbers and possible equations is quantum physics possible?
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via the Schrodinger equation or experiment
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What describes the probability of where an electron can be found in a certain location?
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The intensity of the matter field at a certain location
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Define a wave packet.
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A matter field spread out over a limited distance
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What happens when a wave packet interacts with something like a viewing screen?
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The packet collapses into a tiny, particle-like impact (the electron)
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What is uncertain about the electron and it's mechanics?
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It's position and its velocities. Therefore it is measured in a range of positions and a range of velocities.
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Who described quantum uncertainty?
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Werner Heisenberg
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Define the Heisenberg Uncertainty Principle
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The position and velocity of every material particle are uncertain. Although either uncertainty can have any value, the two are related by: X=v-(h/(4pim))
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For a microscopic particle, if X (the position) is reduced, what happens to V and why?
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V expands. Since X is reduced, the location of the particle is made more certain. V has an inverse relationship with X and therefore it expands and the velocity of the particle must be less certain.
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Due to the uncertainty principle, what can be said about the values of X and V for more massive particles.
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They have a smaller range of possibilities, and therefore more certainty.
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What are the values of a highly confined particle?
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Small X, large V
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Why do large objects like a baseball negate quantum mechanics?
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baseball is many times more massive than an electron. This makes it so predictable that quantum uncertainties can be neglected.
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Why did many scientists object to the quantum uncertainty principle?
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nonlocality issues and unreasonable picture of reality.
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Define nonlocality
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sudden alterations in a spread out quantized EM or matter field. Until the moment of impact, an electron is a spread-out matter field (wave packet)
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What is the probability of finding the electron at the point of impact vs finding it elsewhere?
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100% at the point of impact and 0% of finding it elsewhere.
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How big is a wave packet?
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A wave packet can vary in size from mm to km. A photon wave packet from a distant star is spread over many km, but once the photon hits a detector, the whole packet collapses.
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What happens to an interference pattern when a detector is turned on?
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turns into a noninterference pattern.
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What is the most significant practical application of quantum mechanics?
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The explanation of the atomic structure
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What happens to gas when you heat or pass electric currents through it?
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Excites it and causes it to emit radiation in order to get rid of its excess energy.
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How can you measure wavelengths or frequencies of emitted light?
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By a spectroscope.
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How does a spectroscope work?
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Wavelengths of the emitted light entering a prism is bent by a different amounth. The wavelength can be determined by where the light hits the screen. Causes a spectrum.
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What are the different types of spectra?
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Continuous and Line
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Describe a continuous spectrum
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contains an unbroken range of frequencies, spread out in a continuous band of color. Includes glowing solid or liquid, such as the sun or lightbulbs. Blackbody radiation.
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Describe line spectrum.
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Contains a limited number of precise separated frequencies, each appearing as a narrow line. Heat or pass electric current can cause them; there is a different pattern for each gas.
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What are electric discharge tubes used for?
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useful for studying the spectra of atoms
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Why is the planetary model of atoms inadequate?
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electrons are not found in the nucleus, and atoms do not continually radiate energy.
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What are the assumptions of Neils Bohr's theory of the atom?
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Electron moves in a circular orbit, inward pull on the electron gave orbital speed, electron can only be located in certain orbits. emission of radiation by an excited hydrogen atom is do to reducing a quantum of energy as a photon; absorbing a photon increases energy a quantum.
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What atoms did Neils Bohr's theory work for?
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Only one atom -- Hydrogen.
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What was the only assumption of Neils Bohr's theory that was correct?
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The quantum leaps from lower energy orbits to higher energy orbits and vice versa.
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If a hydrogen atom is isolated and at rest, what should the electron's matter field resemble?
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A stationary, unchanging wave. Like a classical standing wave.
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Doing what to an electron will cause quantization of the atom?
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confining the elctron
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What does the Shrodinger equation solve for?
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Standing wave patterns for the electron's matter field (quantum states of the hydrogen atom) AKA orbitals. gives the energy for each quantum state
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What is another term for quantum states of the hydrogen atom?
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Orbitals
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What does the electron cloud display?
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Darker regions have higher matter wave intensity and and electron is more likely to be found there.
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What do the three numbers of the orbital represent?
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The energy and size, the shape, and the orientation in space.
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Describe the shape of the 1s orbital
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Spehrical shape, small volume, electron is likely to be close to the nucleus
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Describe the shape of the 2s orbirtal
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Electron is farther from nucleus, higher energy, and has one node.
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Describe the shape of the 3s orbital
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electron is found farther form nucleus, 2 nodes.
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Describe the p orbital
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three of them along each axis. Dumbbell-shaped and have a nodal plane of origin.
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Describe the d orbitals.
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It is a dumbbell in a doughnut
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What are the F and G orbitals?
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P orbitals of higher energy (3p)
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What are I and J orbitals?
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D orbitals that are like four-leaf clovers.
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What is the ground state?
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The lowest energy level where the electron is closest to the nucleus. The atom cannot radiate energy in this state. There is no lower energy state.
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What is the excited state?
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states corresponding to higher energy levels. The electron is much farther away from the nucleus and it took work to separate them.
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What is the energy when a proton and an electron are far apart (unbound)
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zero
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What are the energies when a proton and an electron are bound?
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negative
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According to Schrodinger's equation, as the quantum number increases, what happens to the energy state?
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increases.
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According to Shrodinger's equation, what does the energy level of a particle only depend on?
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the principal quantum number.
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What is the ionization energy?
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the energy required for an electron to be released from the ground state of an atom. H--> H+ and e-
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What happens when an atom (hydrogen) emits radiation?
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radiation is quantized so an atom must emit at least one photon whenever it radiates
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What does the conservation of energy say about energy states?
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An electron must instantaneously transition from an excited state to a lower-energy state via a quantum jump. This transition is from one standing wave pattern to another.
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What does the difference in a photon's frequency directly correspond with?
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differences between energy levels
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What would electrons with the lowest energy levels emit?
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UV radiation
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What would electrons in the second energy level emit?
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Visible and UV regions of radiation
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What would electrons in the higher energy levels emit?
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infrared and lower frequency radiation
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What does absorption of radiation do to atoms?
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Cause them to get excited; electrons would instantaneoulsy be promoted to a higher energy level.
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What do the lines missing from the continuous spectrum of the sun corresponded with?
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the element known as helium
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Why does Shrodinger's equation not work with more than one atom?
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We are unable to solve his equation with more than one atom, however there are good approximation methods.
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What is the amount of light absorbed related to?
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concentration of the absorbing substance and the color of solutions
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What is the color of solutions due to?
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the amount of absorption of the complimentary color
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What is a laser?
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light amplifications by stimulated emission of radiation
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What does emission of a photon by one atom stimulate?
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the emission of photons from the other atoms (amplifies the emitted light)
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