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53 Cards in this Set
- Front
- Back
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Strong Force |
Short-range but powerful attractive force between nucleons (protons and neutrons) |
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Electromagnetic Force |
Realatively weak but long-range force between electric charges, bonds electrons to nuclei to form atoms |
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Isotopes |
Atoms with the same number of protons (atomic number, Z) but different atomic masses (protons and neutrons, A; varies in neutrons) |
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Hydrogenic atoms |
Have only one electron, are free of electron-electron repulsions |
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Rydberg constant |
Empirical constant with the value 1.097 E-07 m^(-1) |
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Series with n1=1 |
Lyman series (ultraviolet region) |
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Series with n1=2 |
Balmer series (visible region) |
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Series with n1=3 |
Paschen series (infrared region) |
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Series with n1=4 |
Brackett series (infrared region) |
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Wave-particle duality |
Acting as both a wave and a particle, cannot know the linear momentum (the product of mass and velocity) and the location of the particle at the same time |
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Quantization of energy |
An electron can posses only certain discrete energies in an atom |
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Constructive interference |
Positive region of one wavefunction adds to the positive region of another wavefunction to give a region of enhanced amplitude, increasing the probability that an electron will be found in that region |
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Destructive interference |
A positive region of one wavefunction is cancelled by the negative region of another wavefunction, reducing the probability that an electron will be found in that region |
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Principle quantum number |
n, energy and size (1, 2, 3, 4...) |
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Orbital angular momentum quantum number |
l, magnitude of the orbital angular momentum, angular shape of orbital (n-1) |
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Magnetic quantum number |
ml, labels the orientation of the orbital angular momentum and orientation of lobes (-l to +l) |
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Degenerate |
All orbitals with the same "n" value (have the same energy) |
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Nodes |
Positions where either component of the wavefunction passes through zero |
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Radial nodes |
Occur when the radial component of the wavefunction passes through zero |
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Angular nodes |
Occur where the angular component of the wave function passes through zero |
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Boundary surface |
Defines the region of space within which there is a high probability of finding the electron |
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Ground state |
An elements state of lowest energy |
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Pauli exclusion principle |
No more than two electrons my occupy a single orbital and, if two do occupy a single orbital, then their spins must be paired (opposite) |
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Shielding |
Reduction of true nuclear charge to the effective nuclear charge by the other electrons |
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Penetration |
Potential for the presence of an electron inside shells of other electrons |
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Core |
Filled inner shells of electrons |
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Aufbau principle (building-up principle) |
A procedure that leads to plausible ground-state configurations |
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Hund's rule |
When more than one orbital has the same energy, electrons occupy seperate orbitals and do so with parallel spins |
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Spin correlation |
The tendency for two electrons with parallel spins to stay apart from one another and hence to repel each other less |
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Exchange energy |
The extra stability that a parallel spin configuration (^^) gains because the electrons are indistinguishable and interchangeable |
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Metalloids |
Elements that have properties that make it difficult to classify them as metals or nonmetals |
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Octet rule |
Each atom shares electrons with neighbouring atoms to achieve a total of eight valence electrons |
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Resonance |
The actual structure of the molecule is taken to be a superposition, or average, of all the feasible Lewis structures corresponding to a given atomic arrangement |
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Valence shell electron pair repulsion (VSEPR) theory |
Based on a simple idea about electrostatic repulsion and the presence or absence of lone pairs |
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Stereochemically inert |
Lone pairs that do not influence the molecular geometry |
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Valence bond theory |
Considers the interaction of atomic orbitals on separate atoms as they are brought together to form a molecule |
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Molecular potential energy curve |
A graph showing the variation of the energy of the molecule with internuclear separation |
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Homonuclear |
Same element bonded together |
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Heteronuclear |
Two, or more, different elements bonded together |
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Homonuclear diatomic molecule |
Diatomic molecules in which both atoms belong to the same element |
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Promotion |
The excitation of an electron to an orbital of higher energy in the course of bond formation |
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Hypervalence |
Elements that demand the presence of more than an octet of electrons around at least one atom |
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Molecular orbital (MO) theory |
Generalizes the atomic orbital description of atoms in a very natural way to a molecular orbital description of molecules in which electrons spread over all the atoms in a molecule and bind them all together |
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Bonding orbital |
The energy of the molecule is lowered relative to that of the separated atoms if this orbital is occupied by electrons, arises from constructive interference of neighbouring atomic orbitals |
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Antibonding orbital |
The energy of the molecule is higher than for the two separated atoms if this orbital is occupied by electrons, arises from the destructive interference of neighbouring atomic orbitals (indicated by a node between atoms) |
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Molecular orbital energy-level diagram |
A diagram depicting the relative energies of molecular orbitals |
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Nonbonding orbital |
A molecular orbital that consists of a single orbital on one atom, has the same energy as the initial atomic orbitals |
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Ultraviolet photoelectron spectroscopy |
Electrons are ejected from the orbitals they occupy in molecules and their energies determined |
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Minimal basis set |
The smallest set of atomic orbitals from which useful molecular orbitals can be built |
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Inversion |
Consists of starting at an arbitrary point in the molecule, travelling in a straight line to the center of the molecule, and then continuing an equal distance out on the other side of the center |
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HOMO |
Highest occupied molecular orbital, is occupied last |
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LUMO |
Lowest unoccupied molecular orbital, the orbital directly after the HOMO |
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SOMO |
Singly occupied molecular orbital |
