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62 Cards in this Set

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  • Back
What is the key feature of the quantum theory?
Observable outcomes are unpredictable even when the outcomes arise from identical starting conditions. "quantum uncertainty."
What equation of the overall statistics of large numbers and possible equations is quantum physics possible?
via the Schrodinger equation or experiment
What describes the probability of where an electron can be found in a certain location?
The intensity of the matter field at a certain location
Define a wave packet.
A matter field spread out over a limited distance
What happens when a wave packet interacts with something like a viewing screen?
The packet collapses into a tiny, particle-like impact (the electron)
What is uncertain about the electron and it's mechanics?
It's position and its velocities. Therefore it is measured in a range of positions and a range of velocities.
Who described quantum uncertainty?
Werner Heisenberg
Define the Heisenberg Uncertainty Principle
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))
For a microscopic particle, if X (the position) is reduced, what happens to V and why?
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.
Due to the uncertainty principle, what can be said about the values of X and V for more massive particles.
They have a smaller range of possibilities, and therefore more certainty.
What are the values of a highly confined particle?
Small X, large V
Why do large objects like a baseball negate quantum mechanics?
baseball is many times more massive than an electron. This makes it so predictable that quantum uncertainties can be neglected.
Why did many scientists object to the quantum uncertainty principle?
nonlocality issues and unreasonable picture of reality.
Define nonlocality
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)
What is the probability of finding the electron at the point of impact vs finding it elsewhere?
100% at the point of impact and 0% of finding it elsewhere.
How big is a wave packet?
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.
What happens to an interference pattern when a detector is turned on?
turns into a noninterference pattern.
What is the most significant practical application of quantum mechanics?
The explanation of the atomic structure
What happens to gas when you heat or pass electric currents through it?
Excites it and causes it to emit radiation in order to get rid of its excess energy.
How can you measure wavelengths or frequencies of emitted light?
By a spectroscope.
How does a spectroscope work?
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.
What are the different types of spectra?
Continuous and Line
Describe a continuous spectrum
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.
Describe line spectrum.
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.
What are electric discharge tubes used for?
useful for studying the spectra of atoms
Why is the planetary model of atoms inadequate?
electrons are not found in the nucleus, and atoms do not continually radiate energy.
What are the assumptions of Neils Bohr's theory of the atom?
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.
What atoms did Neils Bohr's theory work for?
Only one atom -- Hydrogen.
What was the only assumption of Neils Bohr's theory that was correct?
The quantum leaps from lower energy orbits to higher energy orbits and vice versa.
If a hydrogen atom is isolated and at rest, what should the electron's matter field resemble?
A stationary, unchanging wave. Like a classical standing wave.
Doing what to an electron will cause quantization of the atom?
confining the elctron
What does the Shrodinger equation solve for?
Standing wave patterns for the electron's matter field (quantum states of the hydrogen atom) AKA orbitals. gives the energy for each quantum state
What is another term for quantum states of the hydrogen atom?
Orbitals
What does the electron cloud display?
Darker regions have higher matter wave intensity and and electron is more likely to be found there.
What do the three numbers of the orbital represent?
The energy and size, the shape, and the orientation in space.
Describe the shape of the 1s orbital
Spehrical shape, small volume, electron is likely to be close to the nucleus
Describe the shape of the 2s orbirtal
Electron is farther from nucleus, higher energy, and has one node.
Describe the shape of the 3s orbital
electron is found farther form nucleus, 2 nodes.
Describe the p orbital
three of them along each axis. Dumbbell-shaped and have a nodal plane of origin.
Describe the d orbitals.
It is a dumbbell in a doughnut
What are the F and G orbitals?
P orbitals of higher energy (3p)
What are I and J orbitals?
D orbitals that are like four-leaf clovers.
What is the ground state?
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.
What is the excited state?
states corresponding to higher energy levels. The electron is much farther away from the nucleus and it took work to separate them.
What is the energy when a proton and an electron are far apart (unbound)
zero
What are the energies when a proton and an electron are bound?
negative
According to Schrodinger's equation, as the quantum number increases, what happens to the energy state?
increases.
According to Shrodinger's equation, what does the energy level of a particle only depend on?
the principal quantum number.
What is the ionization energy?
the energy required for an electron to be released from the ground state of an atom. H--> H+ and e-
What happens when an atom (hydrogen) emits radiation?
radiation is quantized so an atom must emit at least one photon whenever it radiates
What does the conservation of energy say about energy states?
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.
What does the difference in a photon's frequency directly correspond with?
differences between energy levels
What would electrons with the lowest energy levels emit?
UV radiation
What would electrons in the second energy level emit?
Visible and UV regions of radiation
What would electrons in the higher energy levels emit?
infrared and lower frequency radiation
What does absorption of radiation do to atoms?
Cause them to get excited; electrons would instantaneoulsy be promoted to a higher energy level.
What do the lines missing from the continuous spectrum of the sun corresponded with?
the element known as helium
Why does Shrodinger's equation not work with more than one atom?
We are unable to solve his equation with more than one atom, however there are good approximation methods.
What is the amount of light absorbed related to?
concentration of the absorbing substance and the color of solutions
What is the color of solutions due to?
the amount of absorption of the complimentary color
What is a laser?
light amplifications by stimulated emission of radiation
What does emission of a photon by one atom stimulate?
the emission of photons from the other atoms (amplifies the emitted light)