AP Chemistry, Chapter 9 Vocabulary
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36 terms
Terms | Definitions |
|---|---|
 valence-shell electron-pair repulsion (VSEPR) model | model that shows hos so many ABn molecules have shapes related to the basic structures and how these shapes can be predicted, if A is a representative element, one of the elements of the p block of the periodic table |
| bonding pair | electrons involved in making bonds |
| nonbonding pair | an electron domain that is located principally on one atom |
| electron domain | region in which the electrons will most likely be found, (region about the central atom), for nonbonding electron pairs - exert greater repulsive forces on adjacent electron domains thus tend to compress bond angles, exert a greater repulsive force on adjacent electron domains than single bonds |
| electron-domain geometry | arrangement of electron domains about the central atom of an ABn molecule or ion |
| molecular geometry | arrangement of the atoms in space |
| linear, linear | 2 electron domains: 2 bonding, 0 nonbonding; s,p atomic orbital set, two sp hybrid orbital set, 180-degrees (CO2) |
| trigonal planar, trigonal planar | 3 electron domains: 3 bonding, 0 nonbonding; s,p,p atomic orbital set, three sp2 hybrid orbital set (BF3) |
| trigonal planar, bent | 3 electron domains: 2 bonding, 1 nonbonding; s,p,p atomic orbital set, three sp2 hybrid orbital set (NO2) |
| tetrahedral, tetrahedral | 4 electron domains: 4 bonding, 0 nonbonding; s,p,p,p atomic orbital set, four sp3 hybrid orbital set (CH4) |
| tetrahedral, trigonal pyramidal | 4 electron domains: 3 bonding, 1 nonbonding; s,p,p,p atomic orbital set, four sp3 hybrid orbital set (NH3) |
| tetrahedral, bent | 4 electron domains: 2 bonding, 2 nonbonding; s,p,p,p atomic orbital set, four sp3 hybrid orbital set (H2O) |
| trigonal bipyramidal, trigonal bipyramidal | 5 electron domains: 5 bonding, 0 nonbonding; s,p,p,p,d atomic orbital set, five sp3d hybrid orbital set (PCl5) |
| trigonal bipyramidal, seesaw | 5 electron domains: 4 bonding, 1 nonbonding; s,p,p,p,d atomic orbital set, five sp3d hybrid orbital set (SF4) |
| trigonal bipyramidal, T-shaped | 5 electron domains: 3 bonding, 2 nonbonding; s,p,p,p,d atomic orbital set, five sp3d hybrid orbital set (C I F3) |
| trigonal bipyramidal, linear | 5 electron domains: 2 bonding, 3 nonbonding; s,p,p,p,d atomic orbital set, five sp3d hybrid orbital set (XeF2) |
| octahedral, octahedral | 6 electron domains: 6 bonding, 0 nonbonding; s,p,p,p,d,d atomic orbital set, six sp3d2 hybrid orbital set (SF6) |
| octahedral, square pyramidal | 6 electron domains: 5 bonding, 1 nonbonding; s,p,p,p,d,d atomic orbital set, six sp3d2 hybrid orbital set (BrF5) |
| octahedral, square planar | 6 electron domains: 4 bonding, 2 nonbonding; s,p,p,p,d,d atomic orbital set, six sp3d2 hybrid orbital set (XeF4) |
| bond angles | decrease as the number of nonbonding electron pairs increase |
| bond dipole | the dipole moment due only to the two atoms consisting in a bond, depends on both the polarities of the individual bonds and the geometry of the molecule |
| valence-bond theory | marriage of Lewis' notion of electron-pair bonds ot the idea of atomic orbitals leading to a model of chemical bonding |
| hybrid orbitals | atomic orbitals on an atom mix to form new orbitals |
| hybridization | the process of mixing and thereby changing atomic orbitals as atoms approach each other to form bonds, according to the valence-bond model - a linear arrangement of electron domains implies sp hybridization |
| sigma bonds | the line joining two nuclei passes through the middle of the overlap region, where the electron density is concentratrically |
| pi bond | the side-to-side overlap of p orbitals, a covalent bond in which the overlap regions lie above and below the internuclear axis, there is no probability of finding the electron on the internuclear axis, weaker than sigma bonds, double bonds consists of one pi bond, and triple bonds consists of two |
| delocalized | when pi bonds cannot be described as individual electron-pair bonds between neighboring atoms |
| molecular orbital theory | explains some aspects of bonding, describing the electrons in molecules by using specfic wave functions called molecular orbitals (MO) |
| molecular orbitals (MO) | have many of the same characteristics as atomic orb (can hold a max of two electrons with opposite spins, definite energy, electron-density can be visualized by using contour representation), but are associated with entire the entire molecule, not just with a single atom, two are formed whenever two atomic orbitals overlap |
| bonding molecular orbitals | lower-energy MO of H2 concentrates electron density between the two hydrogen nuclei |
| antibonding molecular orbital | higher-energy MO has very little elctron density between the nuclei |
| sigma molecular orbitals | MOs whose electron density in both the bonding and the antibonding molecular orbitals of H2 is centered about the internuclear axis, an imaginary line passing through the two nuclei |
| energy-level diagram | represents the interaction between two 1s atomic orbitals and the molecular orbitals |
| pi molecular orbitals | other 2p orbitals overlap in a side-to-side fashion adn thus concentrate electron density on opposite sides of the line through the nuclei |
| paramagnetism | the magnetic behavior of molecules with one or more unpaired electrons, which are attracted into a magnetic field. the more unpaired electrons in a species, the strong the force of attraction |
| diamagnetism | property of substances with no unpaired electrons are weakly repelled from a magnetic field, much weaker effect than paramagnetism |
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