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Organic Chemistry
Ch. 1
42
Chemistry
Undergraduate 2
09/26/2007

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Term
Energy levels
Definition
Schrodinger discovered that each of these corresponds to a different mathematical description of the electron wave.
Term
Orbitals
Definition
A wave function (psi). In terms of probability (psi^2) of finding an electron at some point relative to the nucleus, as the volume inside the boundary surface of an atom, or the region in space where the probability of finding an electron is high.
Term
Wave Functions
Definition
The solutions to arithmetic expressions that express the energy of an electron in an atom.
Term
Principal Quantum Number
Definition
The quantum number n of an electron that describes its energy level. An electron with n = 1 must be an s electron; one with n = 2 has s and p states available.
Term
Boundary surfaces
Definition
The surface that encloses the region where the probability of finding an electron is high (90-95%).
Term
Spin/Spin Quantum Number
Definition
One of the four quantum numbers that describe an electron. An electron may have either of two different spin quantum numbers, + 1/2 or - 1/2.
Term
Pauli Exclusion Principal
Definition
No two electrons can have the same set of four quantum numbers. An equivalent expression is that only two electrons can occupy the same orbital, and only when they have opposite spins.
Term
Nodal surfaces
Definition
A plane drawn through an orbital where the algebraic sign of a wave function changes. The probability of finding an electron at a node is zero.
Term
Hund's Rule
Definition
When two orbitals are of equal energy, they are populated by electrons so that each is half-filled before either one is doubly occupied.
Term
Valence Electrons
Definition
The outermost electrons of an atom. For second-row elements these are the 2s and 2p electrons. The number of these is equal to the number of the element's group number.
Term
Valence Shell
Definition
The maximum number of electrons in the ___________ for period 2 elements is 8.
Term
Ionization energy
Definition
Amount of energy required to remove an electron from some species.
Term
Endothermic
Definition
Absorbs heat
Term
Exothermic
Definition
Gives off heat
Term
Electron Affinity
Definition
Energy change associated with the capture of an electron by an atom
Term
Electrostatic/Coulombic attractions
Definition
Attractive forces between two oppositiely charged particles.

aka ionic bond
Term
Ionic bond
Definition
Chemical bond between oppositely charged particles that results from the electrostastic attraction between them
Term
Bond dissociation energy
Definition
For a substance A:B, the energy required to break the bond between A and B so that each retains one of the electrons in the bond
Term
Polar covalent
Definition
A shared electron pair bond in which the electrons are drawn more closely to one of the bonded atoms than the other
Term
Electronegativity
Definition
A measure of the ability of an atom to attract the electrons in a covalent bond toward itself. Flourine is the most electronegative element.
Term
Electronegative/electropositive
Definition
___________ element attracts electrons.


___________ element donates them.
Term
Electrostatic potential map
Definition
The charge distribution in a molecule represented by mapping the interaction energy of a point positive charge with the molecule's electric field on the van der Waals surface.
Term
Nonpolar
Definition
No polarization of electron distribution.
Term
Bond dipole moments
Definition
The dipole moment of a bond between two atoms.
Term
Dipole moment
Definition
Product of the attractive force between two opposite charges and the distance between them. This has the symbol (mew) and is measured in Debye units (D).
Term
Debye, D
Definition
Unit used for measuring dipole moments. 1 D = 1 X 10 ^ -18 esu*cm
Term
Connectivity
Definition
Order in which a molecule's atoms are connected. Synonymous with constitution
Term
Isomers
Definition
Different compounds that have the same molecular formula.
Term
Constitutional Isomers
Definition
Isomers that differ in respect to the order in which the atoms are connected. Butane and isobutane are examples.
Term
Stereoisomers
Definition
Isomers with the same constitution but that differ in respect to the arrangement between the orbitals of the electron donor and acceptor.
Term
Structural Isomers
Definition
Same as constitutional isomer.
Term
Condensed structural formulas
Definition
Structural formula in which subscripts are used to indicate replicated atoms or groups.
Term
Bond-line formulas/Carbon skeleton diagrams
Definition
Formula in which connections between carbons are shown but individual carbons and hydrogens are not.
Term
Contributing structures/Resonance hybrid
Definition
The various resonance structures that can be written for a molecule.
Term
Localized
Definition
Lewis formulas show electrons as ________.
Shared between two atoms in a covalent bond or unshared electrons belonging to a single atom.
Term
Delocalization
Definition
Association of an electron with more than one atom. The simplest example is the shared electron pair or covalent bond. This is important in conjugated pi electron systems, where an electron may be associated with several carbon atoms.
Term
Tetrahedral angle
Definition
4 bonds at an angle of 109.5
Term
Strong acids/strong bases
Definition
An acid that is stronger than H30+

A base that is stronger than HO-
Term
Oxonium ion/hydronium ion
Definition
The species H30+
Term
Inductive effects
Definition
An electronic effect transmitted by successive polarization of the sigma bonds within a molecule or ion.
Term
Substitution
Definition
Chemical reaction in which an atom or a group of a molecule is replaced by a different atom or group.
Term
Nucleophiles
Definition
An atom or ion that has an unshared electron pair which can be used to form a bond to carbon. These are Lewis bases.
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