Advanced Inorganic Chemistry – Exam 1 Vocabulary

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Symmetry Operation
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an action performed on a molecule or ion (i.e. rotation or reflection) that it leaves it that it is apparently unchanged (looks the same before and after).
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Symmetry Element
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a characteristic property of a molecule or ion that allows a symmetry operation to take place.
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Point Group
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entire set of specific symmetry operations (or elements) which describes an object’s symmetry.
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Identity operation (E)
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molecule is unchanged (or underwent a 360-degree rotation, same result)
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n-fold rotation (Cn)
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a 360-degree/n rotation along an axis that leaves the molecule apparently unchanged
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Principle (rotation) axis
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the axis with the highest Cn; defined to be z-axis
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Vertical mirror planes (sigma v and sigma d)
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contain the principal axis of rotation (most of these are sigma v)
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Arrhenius acids/bases
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acids produce H+, bases produce OH-
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Bronsted-Lowry acids/bases
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acids are proton donors, bases are proton acceptors
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Lewis acids/bases
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acids are lone pair acceptors and bases are lone pair donors.
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Solvent system – acids/bases
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some solvents can auto-dissociate into cations and anions (like water into hydronium and hydroxide). ~Solutes increasing the concentration of solvent cation are acids. ~Solutes increasing the concentration of solvent anion are bases.
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Frontier Orbital
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acid contains the LUMO of suitable symmetry to interact with the HOMO of the donor (base)
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Levelling effect
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the strongest acid that can exist in a solvent is the cation of the solvent’s autodissociation; the strongest base that can exist in the solvent is the anion of the solvent’s dissociation.
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Solvent-system acid-base theory
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an acid is a substance that increases the amount of the cation of the solvent’s autodissociation; a base increases the amount of the anion of the solvent’s autodissociation
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Ionic liquids
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salts that a liquids around room temperature
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Supercritical fluids
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physical state where liquid and gas states are indistinguishable
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Superacid
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more efficient proton donor than sulfuric acid (pKa < -9); formed by dissolving a powerful Lewis acid into a powerful Bronsted acid.
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Hammett function (Ho)
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similar to pKa except that a very poor base (pKa > 0) is used to measure superacid acidity
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Superbase
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base with gas phase proton affinity, enthalpy > 1,000 kJ/mol (similar to Group 1A hydroxides)
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Inductive effects
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electron withdrawing groups decrease basicity
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Steric effects
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bulky groups tend to reduce acid-base reactivity
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Frustrated Lewis pairs
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molecules with both a strong Lewis acid and a strong Lewis base prevented from interacting by sterics.
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Hydrogen bonding
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an attractive interaction between a hydrogen atom from a molecule or a molecular fragment X-H in which X is more electronegative than H…

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