Inorganic Chemistry ACS: Study Guide

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Ionization energy
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energy required to remove the least tightly bound electron from a neutral atom in the gas phase
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periodic trend of ionization energy
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highest at top right-smaller electron=harder to remove
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Why is a half filled subshell so stable?
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it serves to maximize the stabilizing interactions while minimizing the destabilizing interactions among electrons
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exchange interaction
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pie, stabilizing, result of electrons pairing in degenerate orbitals with parallel spin
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pairing energy
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destabilizing, coulomb interaction, pic, energy of electron-electron repulsion in a filled orbital
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Is it easier to ionize a high energy or low energy electrons
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high energy electron-already contains more energy so it requires less energy input
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What happens when a 3d series metal is ionized?
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the first electron to be ionized will come from the 4s orbital, the other s electron will enter the d orbital (4s03dn+1)
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lanthanide contraction
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reduction in atomic radius following the lanthanide series, contrary to the overall trend observed for the periodic table
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lanthanides
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elements 57-71, first appearance of f orbitals, f orbitals are poor at shielding so any electrons dded will have a higher Zeff, shrinking the radius
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Slater’s rules
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tell us what the effective nuclear charge will be, Zeff=Z-sigma, Z is the atomic number, sigma=sum of the number of electrons in a given subtle multiplied by a weighting coefficient (page 1)
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Shielding
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the reduction in charge attraction between the nucleus and electrons due to electrons between the nucleus and the electron in question, it is considered the be between if it has a lower energy
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penetration
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when an electron of a higher atomic orbital is found within the shell of electrons of a lower atomic number, that is to say that an electron of higher energy is found within an orbital of lower energy
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electron affinity
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the difference in energy for a neutral gaseous atom, and the gaseous anion. used interchangeably with electron gain enthalpy. more positive=more stable EA with the additional electron, more positive EGE=more stable with extra electron
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Combination of electron affinity and ionization energy
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electronegativity, overall measure of an atoms ability to attract electrons to itself when part of a compound, fluorine has highest electronegativity
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polarizability
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an atoms ability to be distorted by an electric field, regions of a molecule can take on partial positive or partial negative charge
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Why do we use the hydrogen system approximation
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systems involving multiple electrons are much more complex, and they require the use of quantum mechanics
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What is the formula for the energy of a hydrogen orbital
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E=-13.6(eV)*(Z^2/n^2), h is plancks constant (background on pg 4)
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Energy can be expressed in…
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Joules, wavenumber, inverse centimeters
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quantum number N
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principle quantum number, defines energy and size of orbital
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quantum number L
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orbital angular momentum quantum number, defines the magnitude of the orbital angular momentum, as well as the angular shape of the orbital, L can have values of 0 to n-1.
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quantum number Ml
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magnetic quantum number, describes the orientation of the angular momentum, ml can have values of 0 to +/-1
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quantum number Ms
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spin magnetic quantum number, defines intrinsic angular momentum of an electron, Ms can have values of either +1/2 or -1/2
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Radial wavefunction
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(R(r)), along with the angular wavefunction, gives us the orbitals. With a wave function it is possible to completely characterize a particle, goes to zero at infinity, produce characteristic shapes when graphed
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Radial distribution function
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a plot of R^2(r)r^2, tells us probability of finding an electron at a certain distance from the nucleus, every orbital has a different radial distribution function and a node on the graph is a region of zero probability
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Bohr radius
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the most probably distance to find the electron in a one proton, one electron system (52.9 pico-meters)
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What orbitals correspond to l=0 through l=4
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L=0=s, L=1=p, L=2=d, L=3=f, L=4=g
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Building up principle/Hund’s rule
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when degenerate orbitals are available for occupation, electrons occupy separate orbitals with parallel spin
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Pauli exclusion principle
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no more than two electrons can occupy a single orbital, and to do so, their spins must be paired
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Descibe VSEPR
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purpose is to predict molecular geometries, basic assumption is that regions of enhanced electron density take positions as far apart as possible in order to minimize repulsive forces.
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Relative repulsion strengths VSEPR
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lone pair> multiple bonds> single bonds
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Valence bond theory
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explains chemical bonding by considering the overlap of tomic orbitals, wave patterns of atomic orbitals interfere constructively to form a bond, sigma is formed when orbital overlap has cylindrical symmetry, pi bond forms when they overlap side by side after the formation of a sigma bond
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How is hybridization used in valence bond theory
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explains bonding where the number of equivalent bonds exceeds the number of valence orbitals
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Effect of a lone pair on geometry?
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it pushes strongly against all other substituent. It is the strongest force governing the shape of a molecule
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Molecular orbital theory
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an improvement over valence bond theory in that the bonding description extends to all atoms in a molecule and handles polyatomic molecules, atomic orbitals combine to form molecular orbitals which are delocalized descriptions of electron distribution
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MO theory assumptions
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orbital approximation, linear combinations of atomic orbitals
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Orbital approximation
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the wave function describing all of the electrons of a molecule can be written as a product of the one electron avefunctions
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linear combination of atomic orbitals
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the superposition of multiple atomic orbitals of same type along with weighting coefficients
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H2 and H2-like molecules
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the 1s orbitals are of equal energy so they lie at the same level of the diagram, atomic orbitals combine to form one sigma orbital which is lower in energy than one anti bonding sigma orbital which is higher in energy
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Li2 through N2 (period 2)
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energy contributing to each atom is the same, 2s orbitals combine to form a bonding 1sigmag and an anti bonding sigmau, as well as a bonding 2sigmag, although that MO is mainly 2p in character. 2p combine as follows: lowest energy orbitals are two degenerates 1piu followed by 2sigmag. Following that is anti bonding orbital 1pig (doubly degenerate) ad 2sigmau
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Period 2: O2, F2 etc, why not Ne2?
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difference is MO diagram’s relative energies of the bonding orbitals piu and pig
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H-X
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H is something that bonds through 2p and 2s orbitals, relative energies of the atomic orbitals are taken into account because there are two separate atoms, H1s is usually higher in energy, 4 atomic orbitals of X will mix with 1s of H to give 5 molecular orbital. Anti bonding is mostly H in character while the other 4 are mostly X
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X-Y
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relative energies are taken into account, more electronegative=lower energy of orbitals
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Relative energies of MOs
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4sigma>2pi>3sigma>1pi>2sigma>1sigma
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Plyatomic MO
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must use approximations of MO theory. Linear combinations of Atomic orbitals create a cumulative approximation of the atomic orbitals of its constituent atoms, compare orbitals to determine what will mix
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LCAO notation
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a,b=nondegenerate, e=doubly degenerate, t=triple degenerate
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LCAO energies
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lowest=a (nondegenerate) intermediate=e highest=t
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LCAO
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linear combinations of atomic orbitals
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Bond order
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a method to assessing overall bond strength between two atoms in a molecule, higher bond order=stronger bond, assesses net number of bonds between two atoms
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Calculating bond order
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(bonding-antibonding)/2
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How to assign bonding character-bonding
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a bonding orbital will lie lower in energy than its substituent atomic orbitals
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How to assign bonding character-nonbonding
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a nonbonding orbital will equal in energy to its corresponding atomic orbitals
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How to assign bonding character-antibonding
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an antibonding orbital will lie higher in energy than its substituent atomic orbitals
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HOMO interactions
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highest occupied molecular orbital, highest energy electrons reside
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LUMO interactions
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lowest unoccupied molecular orbital, it is the energy level directly above the homo
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Importance of HOMO/LUMO
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critical to electron structure, when excited an electron is promoted from HOMO to LUMO. bonding and anti bonding characteristics determine stability, the frontier orbitals are the point of interaction and basis of understanding for molecular interaction
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paramagnetism
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if there are two unpaired electrons
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metallic bonding
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the bonding and ordering of metals into pure solids or solid solutions, viewed as enormous molecules with continually overlapping atomic orbitals
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ionic bonding
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ions of different elements held together in rigid, symmetrical arrays as a result of attraction between their opposite charges
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lattice
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a 3D infinite array of lattice points which define the repeating structure of a crystal
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unit cell
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an imaginary, parallel sided region from which the entire crystal can be built, such that it fits perfectly together, giving rise to a crystal system.
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7 types of crystal systems
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cubic, tetragonal, orthorhombic, monoclinic, triclinic, rhombohedral, hexaganol
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Primitive unit cell
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contains only one lattice point
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body centered
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two lattice points per unit cell
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face centered
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four lattice points per unit cell
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body centered cubic
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3D version of body centered
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close packed
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structure type with least unfilled space
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coordination number
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the number of nearest neighbors, number of other spheres that a single sphere is touching in the unit cell
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cubic close packed
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ABCABC repeating layer of spheres (ABAB results in hexagonally close packed)
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face centered cubic
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same thing as cubic close packed
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hole
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unoccupied space between spheres, can be octahedral, where they lie between triangles and form a hexagon, or tetrahedral where it is formed by a planar triangle of touching spheres
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polymorphism
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the ability of a metal to adopt different crystal structures based on the temperature and pressure
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alloy
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a blend of different metals, more formally called a solid solution
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substitutional solution
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when a solute metal atoms take up the positions of solvent metal atoms in the crystal structure
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interstitial solid solution
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when the solute metal atoms take up positions in the holes of the solvent crystal structure
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lattice enthalpy
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the standard enthalpy change of accompanying the formation of a gas of ions from a solid, measure of strength of the solid
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born haber cycle
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a type of flow chart used to determine the lattice enthalpies and other parameters governing how a solid behaves
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van der waals interaction
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non electrostatic contributions to the lattice enthalpy, the london dispersion interaction is the most dominant VDW interaction, the transient fluctuations in electron density that result in temporary, induced dipoles
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non-stoichiometric compound
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substance that exhibits variable composition but retains the same structure type
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conductor
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a substance with an electric conductivity that decreases as temperature is increased
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semi conductor
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a substance with an electric conductivity that increases as temperature is increased
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insulator
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negligible conduction, but if it is possible to measure, it increases with temperature
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super conductor
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have zero resistance below a critical temperature
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band
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a near continuous array of energy levels, due to the large number of symmetrically oriented atomic orbitals in a solid with very similar energy levels
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band gap
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a separation of bands, due to there being no energy value for the molecular orbital
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s/p band
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the bands built from s and p orbitals
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fermi level
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the highest occupied energy level in a solid at T=0
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parameters for a substitutional solid solution?
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atomic radii of elements are within 15% of each other, crystal structures of two pure metals are the same (directional forces are compatible), electropositive characteristics of both compounds are similar, otherwise electron transfer would be likely
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parameters for an interstitial solid solution
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usually form between metals and small groups, small atom must not transfer electrons or there would be an ionic species, must have a radius all enough to fit in the hole (.414 * radius of metal)
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Most stabilizing influence on a solid?
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lattice enthalpy
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high lattice enthalpy effect on solid
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if high charge and small distance, strongly stabilizing, at highest when tightly packed and ion charge is dense
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low lattice enthalpy effect on solid
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is small charge and large distance the solid is not stable
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born mayer equation
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allows us to estimate the lattice enthalpy from charge and separation at T=0
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Why does solubility depend on lattice enthalpy
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solubility is a product of enthalpy and hydration enthalpy. lattice enthalpy is the energy required to break apart an ionic solid so the solubility is dependent on that value. If thee is a large difference between ionic sizes, the compound is likely to be soluble in water because the ways in which lattice enthalpy and hydration enthalpy depend on the radius (difference in size increases=lattice enthalpy decreases=hydration enthalpy increase)
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solvent levelling
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the ordering of water molecules around a dissolved ion. the more charge dense an ion is, the more it order the water. This is entropically unfavorable, so it acts against processes that seek to break apart ions in solution
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Discuss band theory
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connected to MO theory, continuum of overlapping orbitals, lowest energy orbitals have no nodes between neighboring atoms, highest energy orbitals have nodes between every pair of neighbors, the energy separation between neighboring orbitals approaches zero, creating a near continuous energy spectrum
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band theory s band
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forms between s orbitals
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band theory p band
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forms between p orbitals
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conductors and band theory
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partially filled bands at low energy levels so the electrons are promoted easily, vigorous vibrations, such as those due to thermal energy, disrupt the band structure and decrease conductivity
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insulators and band theory
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filled bands with a large energy differential separating them, filled band is called the valence band and the next higher band is called the conduction band
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types of semiconductors
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intrinsic semiconductor, extrinsic semiconductor, n-type, p-type
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intrinsic semiconductor
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filled s band and empty p band, energy gap is very small so the electrons can be promoted by thermal energy, promotion of electrons results in positive holes in the valence band amounting to a charge separation, which allows current to flow,
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extrinsic semiconductor
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a material gains the ability to be a semiconductor because of intentionally added impurities, which increase the number of electron carriers
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N-type
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n means negative, dopant supplies additional electrons to the solid structure, these electrons like below the valence band in energy and close to the conduction band so the gap is much easier to jump
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P-type
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p means positive, the dopant material has less valence electrons than the parent material. the holes it creates lie just above the valence band in energy, so electrons can jump to the acceptor band to allow current to flow
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what conditions are needed for electrons to flow through a solid
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a small energy difference and unfilled orbitals
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lewis acid
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electron pair acceptor
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lewis base
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electron pair donor
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bronsted lowry acid
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proton donor
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bronsted lowry base
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proton acceptor
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hard acids bond in order of
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I<Br<Cl<F
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soft acids bond in order of
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F<Cl<Br<I
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soft acids/soft bases
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larger, more polarizable
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hard acids/hard bases
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smaller and more charge dense
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HSAB bonding patterns
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hard acids/bases to hard acids/bases, soft to soft
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How does covalence apply to HSAB
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cation covalence increases as size of anion increases, anion covalence increases and size of cation decreases, covalence increases as charge increases, covalence in larger for non-noble configurations
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what contributes to the gibbs energy of complex formation? (other than type of bond formed)
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competition with solvent, rearrangement of subsituents of the acid and base that may be necessary for formation of the complex, steric repulsion between substituents on the acid and base
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criteria for categorization of HSAB
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no definite criteria, based on experimentally determined evidence usually relating to complex formation
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amphiprotic substance
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a molecule that can act as both a bronsted acid and base
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relationship between a strong acid and its conjugate base
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strong acid will have a weak conjugate base, strong base will have a weak conjugate acid, strong acid will remain deprotonated, strong base remains protonatedKa
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Ka for a bronsted acid
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Ka=([A-][H3O+])/[HA]
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range and meaning of Ka
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high Ka=one introduced to the solution, HA immediately and completely converts to A- and H3O+ (except for one in every Ka value (10^11 in case of HI)). Strong acids have high Ka and weak acids have small Ka, where almost no molecules lose a proton
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autoprotolysis
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the proton transfer from one water molecule to another
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why is autoprolysis easier to calculate
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it establishes a constant equilibrium, even in neutral water, between hydronium and hydroxy ions, so KaKb=Kw and Kw=[H3O][OH]
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Discuss proton affinity and proton gain enthalpy
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proton affinity (Ap) and proton gain enthalpy (delta ph H naught), relate to acidity enthalpy changes during a proton transfer.PGE is reported as positive and PA is the negative of it. High AP indicated strong basicity, if only slightly negative, it is only weakly basic or possibly acidic
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Proton gain 3 steps
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electron loss, electron gain, combination of H and A, reverse of H-A bond dissociation, proton gain enthalpy is the sum of the enthalpy of all of these steps
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dominant factor in determining acid character
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electron affinity=inversely related to proton affinity, Ae increases left to right, proton affinity increases right to left, as proton affinity decreases, acidity increases, so Ae and stronger acid character have a positive and direct correlation. higher Ae=more stable conjugate base
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discuss solvent levelling
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solvent levelling in water is the fact that any strong acid or strong base in aqueous solution is only as strong of an acid as h3O+, or as strong as a base of OH-. relative strengths of strong acids can be measured by using an anhydrous weak acid as the solvent, same idea can be applied to bases
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equations for Ka and Kb when considering solvent leveling of water
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Ka=([H2Sol][A])/[HA], Kb=([HB][Sol])/[B]
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How is the bronsted definition of aids and bases extended by the solvent system definition
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bronsted definition is only concerned with proton transfer, solvent system defines an acid as any solute that increases the concentration of the cation generated by auto ionization of the solvent. Defines a base as anything that increases the concentration of the anion generated by the auto ionization of the solvent
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aqua acids
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the acidic proton on a water molecule coordinated to the central metal ion
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discuss aqua acids
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acid strength increases as the covalent character of the M-O(H2) bond increases. Across the periodic table, covalence increases left to right, top to bottom. General, the heavier the metal, the stronger the acid will be
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define and discuss hydroxoacids
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the acidic proton is from a hydroxyl group coordinated to a central metal ion, but without a neighboring oxo group
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define and discuss oxo-acids
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the acidic proton is from a hydroxyl group coordinated to a central metal ion, with an oxo-group adjacent to it. stability of conjugate base if primary factor in determining acid strength, conjugate base’s stability is determined by resonance, polarizability and charge density
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oxo acid generalizations
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non metals form acidic oxides because electronegativity, metals form basic oxides, going down a group, atoms are bigger, polarizes water better and higher hydration enthalpy and entropy, amphoteric compounds form weak acids and weak bases, bases donate electron density, HSAB makes conjugate less stable by making it more soluble
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types of non aqueous solvents
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liquid ammonia, hydrogen fluoride, anhydrous sulfuric acid, dinitrogen tetroxide
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lewis acidity in alkali metals
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act as lewis acid in water, forming hydrated ions
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lewis acidity in group 13
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boron tri-halides act as lewis acids, acid strength increases with atomic mass of the halogen, aluminum halides form dimers in the gas phase, and are used as lewis acid catalysts
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lewis acidity in group 14
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except carbon, group 14 elements exhibit hypervaalence and act as lew acids, tin (II) chloride acts as both a lewis acid and a lewis base
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lewis acidity in group 15
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oxides and halides of the heavier elements act as lewis acids
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group 16
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sulfur dioxide can act as a lewis base when it forms a complex with trialkylamine that acts as a lewis base, sulfur trioxide is a strong lewis acid
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halogens
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bromine and iodine act as mild lewis acids
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difference between hard-hard and soft-soft interactions
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H-H and S-S are more thermodynamically stable than H-S, S-S is more covalent in character, H-H is more ionic in character, S-S are more exothermic
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factors influencing the gibbs energy of complex formation
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competition with solvent, rearrangement of substituents, steric repulsion
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reduction
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gain of electrons
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oxidation
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loss of electrons
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reducing agent
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the species which supplies the electrons (it is oxidized)
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oxidizing agent
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the species which receives the electrons (it is reduced)
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redox couple
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reducing agent + oxidizing agent
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significance of oxidation numbers
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used to describe the ionic state of an atom
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why do we write half reactions to express reduction potentials?
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it follows the movement of electrons, breaking a reaction into half reactions to separate reduction and oxidation gives us a clear view of electron transfer , and simplifies balancing a reaction
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Why is the electrochemical series so hard to predict
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it involves a number of thermochemical cycles, including heat of sublimation, ionization energy, standard enthalpy of hydrations, none dissociation energy, and the overall reaction enthalpy
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effect of multiplying a half reaction
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does not change potential but does change the free energy
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what values of K and E indicate a spontaneous reaction
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if E>0 and K>1 the thermodynamics are favorable (spontaneous)
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anode
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site of oxidation
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cathode
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site of reduction
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galvanic cell
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an electrochemical cell in which a reaction drives an electric current which travels though an external circuit for measurements
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equation for gibbs free energy involving the standard cell potential
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Delta G naught=-nFEnaught, F=9.648*10^4 (faraday) and n is the number of electrons
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strong oxidizing agent
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E naught is large and positive
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strong reducing agent
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E naught is large and negative
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Nernst equation
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gives cell potential at any composition, gives delta r G value,
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under what conditions might a reaction be thermodynamically favorable but kinetically slow
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if E naught > 0, it is spontaneous, but if it requires the movement of multiple electrons simultaneously it will be slow
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discuss the pH dependence of redox reactions
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as pH increases, E decreases. As pH decreases, E increases, this is due to the fact that any redox reactions require H+ ions, and a greater abundance of them increase the amount of current that can be transferred
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passivating layer
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kind of ‘skin’ of a metal oxide that forms over a metal’s surface, which protects the metal from reacting further, forms when the metal begins to react with water or acid and sticks to it, encapsulating it. not necessarily used but utilized so that the metal will not corrode in open air
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what conditions will make water an oxidizing agent
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this will happen spontaneously if the metal is from the s-block, group 3 to group 9, or a lanthanoid. If the standard reduction potential for a metal is negative, it will be oxidize by 1M acid. H2 forms as the reaction progresses
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what conditions will make water a reducing agent
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if the standard reduction potential for a redox couple is 1.23 V or higher, they can oxidize water. Because H+ is produced in the reaction, a higher pH encourages formation of the products, these types of actions are spontaneous but kinetically very slow because the number of electrons that need to be moved
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stability field of water
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the range of values of potential for which water is thermodynamically stable toward both oxidation and reduction, stable between pH 4 and pH 9, between redox potentials of H+/H2, O2/H2O
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Under what conditions will water be unstable
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it will be unstable outside of the boundaries previously stated
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disproportionation
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the oxidation number of an element that is simultaneously raised and lowered, such that a species at a certain oxidation state is converted to a species that is more oxidize, and a species that is reduced. In a latimer diagram, if the potential on the right is higher than the potential on the left, it will tend to disproportionate
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comproportionation
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the reverse of disproportionation, two species of the same element n different oxidation states will form a common product of the same oxidation state. In a latimer diagram, if the potential on the left is higher than that on the right, it will tend to comproportionate
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How would i use the standard cell potential to determine the solubility product
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if an aqueous metal ion and its precipitate are in equilibrium, the solubility product (Kip) can be determined by the reduction potentials for the half reaction that returns the metal to its neutral state, both as an individual ion and as the precipitate
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latimer diagram
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a type of flow chart that are used to follow the oxidation and reduction of a particular element or compound, can be used to quickly determine the number of electrons transferred in a redox reaction, and it gives the standard potentials associated with them
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symmetry operator E
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identity operator, always there
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symmetry operator Cn
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rotation by 360/2, if n=2, only one operation involved. if n=3, two operations associated with it, principal axis
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principal axis
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the highest order rotational axis and it defines the z-axis of the molecule
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symmetry operator sigma mirror plane
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a mirror plane is a vertical mirror plane, sigmav, is it contains the z-axis, as defined by rotational symmetry. The horizontal mirror plane, sigmah, is the plane of the molecule perpendicular to sigmav, there can also be a dihedral mirror plane, sigmad, which bisects two c2 axes
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symmetry operator I
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center of inversion, inversion operator has each atom of the molecule projected through a single point, and out the same distance on the other side, succeeding to interchange diametrically opposite in pairs, only Oh, Dinfinityh, D4h, D2h, and Ci point groups have an inversion operator
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symmetry operator Sn
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improper rotation/ screw axis. This consists of a rotation through a certain angle followed by a reflection in a mirror plane perpendicular to the rotation
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high symmetry groups
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Dinfinityv, Cinfinityv, Ih, Oh, Td
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low symmetry groups
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Cs, Ci, C1
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irreducible representation
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the row of characters for the given symmetry species
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symmetry in a polar molecule
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3 rules to account for permanent dipole, cannot be polar if it has a center of inversion (Oh, DInfinityh, D4h, D2h, Ci), cannot have an electric dipole moment perpendicular to any mirror plane, molecule cannot have an electric dipole moment perpendicular to any axis of rotation
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symmetry in a chiral molecule
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a molecule cannot be chiral if it has an improper rotation axis or a mirror plane
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relationship between degrees of freedom and character tables
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for molecule of N atoms, there are 3N degrees of freedom, 3 are translational, 3 are rotational, 3N-6 vibrational modes (if non linear) if linear, there is no rotation about the axis of the molecule so there are 3N-5 vibrational modes in a linear molecule
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IR active
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the symmetry species of the vibration must be the same as that of x, y, or z in the character table
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Raman active
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the symmetry species of the vibration must be the same as that of xy or x^2
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SALC
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symmetry adapted linear combination of atomic orbitals, atomic orbitals which can be combined to a single symmetry type in order to construct a MO diagram
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how does an irreducible representation help us identify Raman active and IR active
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if a molecule has a center of inversion, none of its nodes can be both IR and Raman active, an active vibrational mode is IR active if it has the same symmetry as a component of the electric dipole moment (x,y,z rotations). A vibrational mode is Raman active if it has the same symmetry as a component of the molecular polarizability (quadratic functions)
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nomenclature of coordination compounds
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to write a formula, cation then anion followed by ligands in alphabetical order. to name the compounds, first the ligands are listed alphabetically (with prefix) then followed by the metal and its charge. if there is bridging it has ”
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mono
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one point of attachment
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bi
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two points of attachment
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tri
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three points of attachment
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how do you identify mono-bi-ti dentate ligands
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the atoms which bind to the central metal typically have lone pairs, or carry a negative charge. It is important to note that carbon is rarely the site of attachment
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ambidentate ligand
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one which has multiple donor atoms, but only binds through one, typically has a negative charge, resonance stabilized
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chelate
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a complex which forms when a polyentate ligand binds to a metal with more than one of it’s donor atoms. They tend to bind at adjacent sites in a cis configuration
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in terms of coordination chemistry, what is an acid and what is a base
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metal ion is lewis acid (EP acceptor) and the ligand is a lewis base (EP donor)
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Factors that govern the coordination number of a complex
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size of central atom or ion, steric interactions between ligands, electronic interactions between central atom/ion and ligands
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Effect of large atomic radii on coordination number of complex
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larger radii=higher coordination numbers
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what group on the periodic table known to form 2 coordinate complexes
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group 11
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favored symmetry and point group for four coordinate complexes
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tetrahedral, a small cation and large ligands. If the ligands are the same the point group is Td. If central ion has a d8 configurations, it will adopt a square planar configuration if all the ligands are the same
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favored symmetry and point group for five coordinate complexes
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uncommon, but if it does happen it will be square pyramidal (c4v) or trigonal bipyramidal (d3h). Steric distortions are common and deviations from ideal geometry happen frequently
question

favored symmetry and point group for six coordinate complexes
answer

almost always octahderal, Oh
question

for what atoms/ions will we observe high coordination numbers
answer

f block
question

four types of isomers
answer

linkage isomers, ionization isomers, hydrate isomers, coordination isomers
question

linkage isomers
answer

these form only with ambidentate ligands, and are the result of the different donor atom binding
question

ionization isomers
answer

these occur when a ligand and a counter-ion (dissolved in solution) change places
question

hydrate isomers
answer

occur when water trades places with a ligand
question

coordination isomers
answer

occur when two different complex ions can have the same molecular formula through different bonding orders
question

meridional and facial isomers
answer

only occur for 6 coordinate complexes with octahedral geometry with the formula MA3B3
question

meridional isomers
answer

have one set of ligands around the metal ion’s meridian, the other set along the mermaid perpendicular to the other
question

facial isomers
answer

best visualized by putting all 3 of one ligand into a triangle and the other 3 into a diametrically opposite triangle
question

what isomers are observed for four coordinate complexes
answer

for square planar, on cis ad trans isomers occur. For tetrahedral, enantiomers are the only isomers
question

What isomers are observed for six coordinate complexes
answer

cis/trans, facial/meridional,
question

what is a formation constant and how is it determined
answer

an equilibrium constant denoted by Kf and is a measure of the strength of ligand binding relative to water. Large Kf=inds to incoming ligand well. Kf=[MLlittlen]/[M][L]
question

what is the trend of stepwise formation constants
answer

they tend to decrease with the addition of eah successive ligand
question

what causes a stepwise formation constant to deviate
answer

if Kf(n+1) is greater than Kfn it is indicative of a change in coordination, show that the complex is more stable at a lower coordination number than for the previous set of ligands
question

chelate effect
answer

a complex with chelating ligands is more stable than one with non chelating ligands, as observed by formation constants
question

What does the tanabe sugano diagram depict
answer

the energies of electronic states of complexes as a function of the ligand field strength. It shows terms splitting into different microstates
question

how are the term energies expressed on the axes
answer

E/B on y plotted against delta/B on x. B is rajah parameter
question

what does a curved line mean on a tanabe sugano diagram
answer

it is the result of mixing orbitals due to the same symmetry
question

what is the no crossing rule in a tanabe sugano diagram
answer

if the increasing ligand field causes two weak field terms to approach, they bend apart rather than cross
question

what is the name of the term of lowest energy, where is it on the graph?
answer

ground term, x axis
question

what spectrum does a tanabe sugano graph represent
answer

the electronic absorbance spectrum
question

what transition are forbidden on tanabe sugano
answer

transitions which change the spin state
question

what are the racah parameters
answer

the energy due to repulsions, and is expressed as a collection of 3 terms, A, B, and C. A is the average of total inter-electron repulsion, B and C are repulsion energies between individual d electrons
question

what is microstate
answer

micro states are the different ways in which electrons can occupy orbitals
question

what is a term
answer

spectroscopically distinguishable energy levels of micro states with the same energy when electron-electron repulsions are considered
question

how do electron-electron repulsions affect a spectrum
answer

they result in multiple absorptions, if they are treated as negligible then the micro states have the same energy
question

what energies are spin forbidden
answer

the lowest energies
question

what are the two most important properties of 3-d series and light elements (in order)
answer

relative orientation of electron spin, relative orientation of orbital angular momenta
question

big S
answer

S is the total spin quantum number, which comes from the relative orientations of individual spins
question

big L
answer

L is the total orbital angular momentum quantum number which comes from the relative orientation of individual orbital angular momenta of each electron
question

how do we assign values to L
answer

L can take on values of l1+l2, l1+l2-1…[l1-l2]
question

what is spin orbital coupling
answer

the relative orientation of spin and angular momenta of each electron
question

how do we assign values to S
answer

S can take on values of s1+s2, s1+s2-1…[s1-s2]
question

what are the ranges of ML and MS
answer

Ml can range from positive L to negative L so it encompasses 2L+1. MS can range from positive S to negative S so it encompasses 2S+1
question

russle saunders coupling
answer

used for 3d metals, the process of combining angular momenta by first summing spins, then orbital momenta, and combining them
question

What is the word for total spin? What is the abbreviation and how is it determined?
answer

total spin is called multiplicity, abbreviated with P,it is a 2S+1
question

describe the two steps using hund’s rule to assign energies
answer

1. identify the micro state with the highest value of MS. This tells us the highest multiplicity. 2. Identify the highest permitted value of ML for the multiplicity. This tells us the highest L value for multiplicity. we are only concerned with the lowest energy, which is what this rule tells us how to find
question

how do you identify the ground term in a set of terms
answer

by using hund’s rules
question

corresponding letter and orbital L=0
answer

S, A1g
question

corresponding letter and orbital L=1
answer

P, T1g
question

corresponding letter and orbital L=2
answer

D, T2g, Eg
question

corresponding letter and orbital L=3
answer

F, T2g, A2g, T1g
question

corresponding letter and orbital L=4
answer

G, A1g, Eg, T1g, T2g
question

What metal is L considered a very important factor?
answer

3d metals
question

for wat metals is L not a very important factor
answer

4d and 5d because spin, orbit coupling is the most important factor in determining energy
question

two types of charge transfers
answer

ligand to metal charge transfer, metal to ligand charge transfer
question

charge transfer
answer

occur when an electron that is primarily ligand or metal in character oigrates to an orbital that is primarily metal or ligand in character (opposite)
question

solvatochromism
answer

variation in the transition frequency with change in the solvent permittivity. this is a better indicator of a metal/ligand interaction than a ligand-ligand or metal-metal interaction
question

When do LMCT reactions occur in the visible region
answer

two causes, may be a result of the ligand having high energy lone pairs or because the metal has a low lying empty orbital
question

In a metal complex, what reduces what
answer

the ligand reduces the metal ion
question

are LCMT and MLCT localized or delocalized
answer

localized
question

what characteristics of the metal atom will give a strong CT band
answer

a metal ion with a high oxidation state
question

what characteristics of the complex makes a MLCT likely to occur
answer

if a complex has ligands with low lying pi star orbitals, especially with aromatics, a MLCT is likely to occur
question

describe the relative proximity of ligand and metal orbitals in a MLCT
answer

the metal d orbitals are low in energy, lying very close to the empty ligand orbitals
question

what are the most common ligands to result in MLCT
answer

diimines
question

Emax
answer

a measure of the absorption strength for ligand field transitions
question

what is the approximate Emax for octahedral complexes
answer

100
question

approximate Emax for tetrahedral
answer

250
question

approximate Emax for square planar
answer

100
question

transition dipole moment
answer

the impulse of a transition on an electromagnetic field, which is a measure of the strength of transitions
question

transition dipole moment for an allowed transition
answer

nonzero
question

transition dipole moment for a spin forbidden transition
answer

zero
question

describe spin allowed transitions in terms of a singlet to triplet transition and the value of ds
answer

singlet (s=0) cannot undergo reaction to triplet (s=1), it is a forbidden transition
question

what can relax the rules regarding spin transition
answer

spin orbital coupling can relax the spin transition rules, but these transitions are weak, although they do not increase with atomic mass
question

what are the laporte selection rules
answer

in a centrosymmetric molecule or ion, the only allowed transitions are those accompanied by a change in parity. Transitions from g to u in terms are allowed but those from g to g and u to u are forbidden. For s and d orbitals, forbidden transitions are s-s, p-p, d-d, f-f, s-d, p-f, while the allowed transitions are s-p, p-d, d-f
question

what can relax the laporte rules
answer

the selection rules are relaxed if the complex departs (slightly) from the perfect centrosymmetry in its ground state, or if asymmetric vibrations destroy the center of inversion
question

based on energies of the transition, classify them as spin and laporte allowed or forbidden
answer

E<1, SF (spin forbidden), LF (laporte forbidden) E<10 SA (spin allowed), LF E<100 SA, LF E<5000 SA, LA
question

ligand field splitting parameter
answer

the energy difference between sets of orbitals of different energy i the same sub shell
question

barycenter
answer

the energy level corresponding to a spherical distribution of electric charge
question

what will cause delta naught to increase
answer

it will increase with an increasing oxidation state, and down a group. Corresponds to smaller size having more highly charged ions which results in shorter metal-ligand bond distances
question

ligand field stabilization energy
answer

it is stabilizing energy imparted to a d orbital spltting into e.g. and t2g orbitals relative to the barycenter
question

pairing energy
answer

the coulomb repulsion that results from electrons pairing. Pairing energy is taken into account only when the pairing of electrons is in addition to that of a spherical field
question

define weak field a strong field cases
answer

weak field is when delta naught is less than P, strong field is when it is more than P. In the weak field case, the electron will be promoted to e.g. orbital and in the strong field case it will stay in t2g
question

high spin
answer

when there are now more electrons unpaired than in a free ion
question

low spin
answer

when there are more electrons paired than otherwise
question

for 3d ion complexes, considering the ligands, how do high spin and low spin correlate to the spectrochemical series
answer

low spin complexes generally have ligands that are high in the spectrochemical series, while high spin complexes generally have ligands that are low in the spectrochemical series
question

diamagnetic
answer

repelled by a magnetic field
question

paramagnetic
answer

attracted to a magnetic field
question

describe the orbital configuration for tetrahedral
answer

t2 orbitals are higher in energy than e orbitals, they are separated by delta t, with the t2 orbitals lying at 2/5 delta above the barycenter, and e orbitals at 3/5 below it. always high spin
question

describe the orbital configuration for square planar
answer

highest in energy is x2-y2, followed by xy, then yz, then zx, and z2 is the lowest energy. square planar is always higher energy than tetrahedral, favored for d8, low spin is favored
question

what will cause a molecule to experience the jahn teller effect
answer

it is cause by unstable geometry, but more specifically, electros with degenerate spin states in e.g. orbitals
question

what symmetries can we expect to see the jahn teller effect
answer

Oh, C4v, D4h
question

what effect does jahn teller distortion have on a spectra
answer

absorbance peaks wil be asymmetric, both are ground state and the excited state are detected so the peak may have a shoulder or overlapped peaks
question

what are the symmetry labels and degeneracy for a metal s orbital
answer

degeneracy of 1 a1g
question

what are the symmetry labels and degeneracy labels for a metal px, py, pz orbitals
answer

t1u, degeneracy of 3
question

what are the symmetry labels and degeneracy labels for a metal dx2-y2, dz2, orbitals
answer

e1, degeneracy of 2
question

what are the symmetry labels and degeneracy labels for a metal dxy, dyz, dxz orbitals
answer

t2g, degeneracy of 3
question

frontier orbitals
answer

molecular eg and t2g orbitals are the frontier orbitals. when considering only sigma bonding, the t2g molecular orbitals are entirely metal in character and non bonding
question

ligand pi orbitals include salcs of what symmetry
answer

t2g, it is delocalized
question

pi donor ligands are also known as what
answer

pi bases, they have filled pi orbitals about the M-L axis and are lower in energy than sigma orbitals
question

pi acceptor ligands are also known as what
answer

pi acids, they have empty pi orbitals available for occupation about the M-L axis
question

what electrons are ejected in X-ray absorbance spectroscopy
answer

electrons are ejected from the core
question

what is the range of energy for photons
answer

0.1 keV to 100keV
question

what does the photon energy correspond to
answer

related to binding energy of core electrons
question

what is the edge region
answer

where the photo electron energy is in the range of Ei-Ei+10eV
question

what is the K edge (pre edge)
answer

where the core electrons are not ejected but promoted to higher energy empty orbitals. It provides information on energies of excited electronic states and local symmetry if the atom
question

what is the continuum
answer

when referring to a continuous absorption spectrum, a continuum is where absorbance is shown continuously throughout a given range (think from initial to infinity)
question

how do dipole transitions appear in the spectra
answer

dipole transitions are forbidden
question

describe the XANES
answer

X ray absorption near edge fine structure, the energy lies between Ei and Ei+10eV. It gives information on oxidation state, coordination environment, and the subtle geometric distortions. It can be used as a fingerprint, as it is characteristic of the environment and valence state, ad also can be used to determine the presence and quantity of a compound in a mixture
question

Describe NEXAFS
answer

near edge X-ray absorption fine structure. The energy lies between Ei and Ei + 50eV. It gives information on the orientation of adsorbed molecules
question

EXAFS
answer

extended x-ray absorption fine structure. The energy range is anything greater than the NEXFAS region. The back scattering of photons by adjacent atoms can be detected by observing periodic trends in intensity at energies just above the absorption edge. It provides information on electron density, the number of nearby atoms, as well as the separation of atoms. It will also tell us the bond lengths of species in the amorphous samples
question

what are the relative strengths of dipole and quadripole transitions
answer

dipole transitions are bout 100 times stronger than the quadripole
question

define photoelectron spectroscopy (PES)
answer

the measurement of kinetic energies of electrons emitted by the ionization of a sample that is irradiated with high energy monochromatic radiation. More simply put, a sample is irradiated with a single wavelength light source, and this causes emissions of photoelectrons
question

what is the formula for PES
answer

Ek=hv-Ei
question

what is koopman’s theorem
answer

the ionization energy is equal to the negative of the orbital energy
question

two types of PES
answer

x-ray photoelectron spectroscopy and UV photoelectron spectroscopy
question

XPS (x ray photoelectron spectroscopy)
answer

used to study the and structure of solids. Photons which cause ionizations in samples are photo electrons emitted from an anode. They photo electrons causing the ionization are the result of an ejection of a 1s electron, followed by a 2p electron moving down to fill the vacancy. XPS gives broad signals, half widths are about 1eV.
question

UPS (UV photoelectron spectroscopy)
answer

used the characterize valence shell energy levels and vibrational fine structure. The radiation source is a helium discharge lamp. smaller line widths
question

what does the spectra look like for an ion ejected from a non bonding orbital
answer

single, sharp line. Product is formed in its vibrational ground state
question

what does the spectra look like for an electron ejected from a bonding or anti bonding orbital
answer

extended fine structure with many peaks. it is formed in many vibrational states
question

how can we tell is the electron was ejected from a bonding or anti bonding orbital
answer

if it were ejected from a bonding orbital, it will have a lower frequency than the original molecule. If it were ejected from an anti bonding orbital, it will have a higher frequency than the original molecule
question

what causes peaks to appear on the spectra
answer

appear if the ejected electron has significant influence on geometry
question

what is electron paramagnetic resonance spectroscopy
answer

application of a magnetic field produces different energies in the magnetic angular orientation of electrons (+/- 1/2). We observe the resonant absorption of unpaired electrons
question

what types of atoms is EPR used to study
answer

paramagnetic species
question

what effect does the magnetic field have on the electron
answer

depending on the spin state, it will either raise or lower the energy and the energy difference is observed
question

describe a continuous wave spectrometer
answer

the sample is irradiated with a constant microwave frequency ad a varying magnetic field
question

how do you improve resolution, what causes improved resolution? EPR
answer

improved by using high magnetic fields, which reduces the interactions between paramagnetic centers, which sharpens and simplifies the spectra using pulsed EPR also makes higher resolution by providing time resolutions to make it possible to measure dynamic properties.
question

what is the G value EPR and what is it for a free electron
answer

the g value, or the londe factor, is the measure of the molecule or atom being studied. IT is a product of L, S, and J, the total angular momentum. G for fee electron = 2.0023
question

what perturbs the g value in compounds
answer

spin orbit coupling alters the g value in complexes
question

define isotropic
answer

all 3 g values are the same (along with 3 perpendicular axes)
question

define axial
answer

2 g values are the same
question

define rhombic
answer

all g values are different
question

why is resolution improved in frozen samples vs liquid
answer

in a liquid sample, the molecules are moving so they are difficult to measure
question

describe hyperfine structure
answer

it is a multiplet structure due to coupling of electron spin to magnetic nuclei. A nucleus with spin I will split the EPR line into 2I+1 lines of the same intensity
question

what is cyclic voltammeter and what does it tell us
answer

it tell us the redox potential of a complex and from that we can determine its stability. IT also gives us information of thermodynamic and kinetic properties. The current between two electrodes is measured as the potential difference and it is changed cyclically to produce a triangular waveform
question

working electrode metals
answer

Pr, Ag, Au, or graphite
question

reference electrode metals
answer

Ag/AgCl
question

what two critical species are contained in the solution, how concentrated are they?
answer

a redox couple wit a very dilute solution (micro molar)
question

first step CV
answer

the current is turned on and as it approaches the reduction potential of the redox couple, the reduced species is oxidized at the working electrode and the current starts to flow
question

step 2 CV
answer

the current rises to a peak then decreases as the reduced species is depleted
question

step 3 CV
answer

once the upper limit is reached, the sweep reverses
question

how do we approximate the redox potential
answer

the average of the 2 peaks is the approximate redox potential
question

what is the separation between the oxidation and reduction potential
answer

ideally they are separated by 59mV/#e-

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