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30 Cards in this Set
- Front
- Back
J.J. Thomson |
Discovered first electronApplied high voltage to a partially evacuated tube with a metal electron endObserved a ray was produced from the negative electrode (cathode)As a result named it a cathode ray tubeHypothesized the ray was made of negatively charged particles b/c the negative pole repelled the rayRaisin bun model |
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Robert Millikan |
Determined mass of electronUsed charged oil drops to determine charge of electron by discovering they could be halted by adjusting the voltage across two charged platesUsing Thomson's charge-to-mass ration, he discovered the mass was 9.11x10^-31kg |
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Ernest Rutherford |
Shot alpha particles (8000x mass of electron) at a thin sheet of goldDiscovered most atoms went right through which didn't support Thomson's model (1/8000 particles deflected)Planetary/Beehive model; nucleus with concentrated positive atoms, electrons moved around it |
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Niels Bohr |
Created the idea that electrons travel around energy levels and can jump from level to level when energy is supplied or taken away |
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Heisenberg's Uncertainty Principle |
the idea that it is impossible to know the exact position and speed of an electron at a given time |
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De Brogle |
started the theory that a particle has wave properties |
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Planck's Blackbody Radiation |
Planck's law describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature T. The law is named after Max Planck, who proposed it in 1900. It is a pioneering result of modern physics and quantum theory. |
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Einstein |
proposed that an electron was emitted from the surface of the metal because a photon collided with the electron… |
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Photoelectric effect |
electrons are emitted by matter that absorbs energy from shortwave electromagnetic radiation (ex. visible or UV light) |
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Spectroscopy |
The analysis of spectra to determine properties of their source |
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Emission spectrum |
the spectrum of electromagnetic radiationemitted by an atom; results when an atom is returned to a lower energy statefrom a higher energy level |
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Continuous spectrum |
an emission spectrum that contains all thewavelengths in a specific region of the electromagnetic spectrum |
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Line spectrum |
an emission spectrum that contains only thosewavelengths characteristic of the element being studied |
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Quantum Mechanics |
the application of quantum theory to explain theproperties of the matter, particularly electrons in atoms |
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Electron Probability Density |
the probability of finding an electron at agiven location derived from the wave equations and used to determine the shapesof orbitals; aka electron probability distribution |
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Quantum Mechanical Model |
A model for the atom based on quantum theory and the calculation of probabilities for the location of electrons |
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Quantum Numbers |
numbers that describe the quantum mechanicalproperties of orbitals, from the solutions to Schrodinger’s wave equation |
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Principal Quantum Numbers (n) |
the quantum number that describes the sizeand energy of an atom in orbital |
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Secondary Quantum Number (l) |
thequantum number that describes the shape and energy of an atomic orbital, withwhole number values from 0 to n-1 for each value of n |
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Magnetic Quantum Number (ml) |
the quantum number that describes theorientation of an atomic orbital in space relative to the other orbitals in theatom (+1 and -1) |
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Spin Quantum Number (ms) |
the quantum number that relates to the spin ofthe electron, +1/2, -1/2 |
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Pauli Exclusion Principle |
no 2 electrons in the same atom can be in thesame quantum state |
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Aufbau Principle |
the theory that an atom is “building up” bythe addition of electrons, which fill orbitals starting at the lowest availableenergy before filling higher energy orbitals |
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Hund's Rule |
rule stating that in a particular set oforbitals of the same energy, the lowest energy configuration for an atom is theone with the maximum number of unpaired electrons allowed by the Paul Exclusionprinciple unpaired electrons are represented as having parallel spins.D |
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Duet Rule |
The observation that the complete outer shell of cadence electrons when hydrogen and period 2 metals are involved in bonding |
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Octet Rule |
The observation that many atoms tend to form the most stable substances when they are surrounded by 8 electrons in their valence shells |
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Valence Shell Electron-Pair Repulsion theory (VSEPR) |
A method to determine the geometry of a molecule based on the idea that electron pairs are as far apart as possible |
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Valence Bond Theory |
A theory stating that atomic orbitals overlap to form a new orbital with a pair of opposite-spin electrons
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Sigma Bond |
A bond that is formed when the lobes of 2 orbitals directly overlap end to end |
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Pi Bond |
A bond that is formed when the sides of the lobes of 2 orbitals overlap
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