Term
| Acid-Dissociation Constant (Ka) |
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Definition
The equilibrium constant for the reaction of the acid with water to generate H3O+.
Ka
HA + H2O <==> H3O+ + A-
acid base
^----conjugate acid-base pair----^
Then negative logarithm of Ka is expressed as pKa:
pKa = -log10Ka |
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Term
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Definition
Arrhenius definitions
Acid: dissociates in water to give H3O+
Base: dissociates in water to give -OH
Brønsted-Lowry definitions
Acid: proton donor
Base: proton acceptor
Lewis definitions
Acid: electron-pair acceptor (electrophile)
Base: electron-pair donor (nucleophile)
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Term
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Definition
| The acid that results from protonation of a base. |
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Term
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Definition
| The base that results from loss of a proton from an acid |
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Term
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Definition
Bonding that occurs by the sharing of electrons in the region between two nuclei.
Single Bond: A covalent bond that involves the sharing of one pair of electron
Double Bond: A covalent bond that involves the sharing of two pair of electron
Triple Bond: A covalent bond that involves the sharing of three pair of electron |
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Term
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Definition
| A method of drawing curved arrows to keep track of electron movement from nucleophile to electrophile (or within a molecule) during the course of a reaction. |
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Term
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Definition
| Orbitals with identical energies |
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Term
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Definition
| A measure of the polarity of a bond (or a molecule), proportional to the product of the charge separation times the bond length. |
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Term
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Definition
| The relative probability of finding an electron in a certain region of space. |
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Term
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Definition
| A measure of an element's ability to attract electrons. Elements with higher electronegativities attract electrons more strongly |
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Term
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Definition
| An electron-pair acceptor (Lewis acid). |
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Term
| Electrostatic Potential Map (EPM) |
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Definition
| A computer-calcuclated molecular representation that uses colors to show the charge distribution in a molecule. In most cases, the EPM uses red to show electron-rich regions (most positive electrostatic potential) and blue or purple to show electron-poor regions (most positive electrostatic potential). The intermediate colors orange, yellow, and green show regions with intermediate electrostatic potentials. |
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Term
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Definition
The ratios of atoms in a compound. This doesn't give structural information.
Example: Glucose
CH2O |
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Term
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Definition
| A method for keeping track of charges, showing what charge would be on an atom in a particular Lewis structure. |
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Term
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Definition
| When there are two or more unfilled orbitals of the same energy (degenerate orbitals), the lowest-energy configuration places the electron in different orbitals (with parallel spins) rather than paired in the same orbital. |
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Term
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Definition
| Bonding that occurs by the attraction of oppoistely charged ions. Ionic bonding usually results in the formation of a large, three-dimensional crystal lattice. |
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Term
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Definition
| Atoms with the same number of protons but different numbers of neutrons; atoms of the same element but with different atomic masses. |
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Term
| Line-Angle Formula (aka Skeletal Structure, Stick Figure) |
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Definition
| A shorthand structural formula with bonds represented by lines. Carbon atoms are implied wherever two lines meet or a line begins or bends. Atoms other than C and H are drawn in, but hydrogen atoms are not shown unless they are on an atom that is drawn. Each carbon atom is assumed to ahve enough hydrogen to give it four bonds. |
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Term
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Definition
| A structural formula that shows all valence electrons, with bonds symbolized dashes (-) or by pairs of dots, and nonbonding electrons symbolized by dots. |
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Term
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Definition
| A pair of nonbonding electrons |
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Term
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Definition
The number of atoms of each elements in one molecule of a compound. This doesn't give structural information.
Example: Glucose
C6H12O6 |
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Term
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Definition
| A region in an orbital with zero electron density. |
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Term
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Definition
| A flat (planar) region of space with zero electron density. |
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Term
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Definition
| Valence electrons that are not used for bonding. A pair of nonbonding electrons is ofent called a lone pair. |
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Term
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Definition
| An electron-pair donor (Lewis Base) |
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Term
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Definition
| Atoms generally form bonding arrangements that give them filled shells of electrons (noble-gas configurations). For teh second-row elements, this configuration has eight valence electrons. |
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Term
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Definition
| An allowed energy state for an electron bound to a nucleus; the probability function that defines the distribution of electron density in space. The Pauli exclusion principle states that up to two electrons can occupy each orbital if their spins are paired. |
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Term
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Definition
New Definition:
The chemistry of carbon compounds.
Old Definition:
The study of compounds derived from living organisms and their natrual products. |
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Term
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Definition
| A measure of the acidity of a solution, defined as the negative logarithm (base 10) of the H3O+ concentration: pH = -log10[H3O+] |
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Term
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Definition
| A covalent bond in which electron are shared unequally. A bond with equal sharing of electrons is called a nonpolar covalent bond. |
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Term
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Definition
| A molecule or ion for which two or more valid Lewis structures can be drawn, differing only in the placement of the valence electrons. These Lewis structures are called resonance forms or resonance structures. Individual resonance forms do not exist, but we can estimate their relative energies. The more important (lower-energy) structures are called major contributors, and the less important (higher-energy) structures are called minor contributors. When a charge is spread over two or more atoms by resonance, it is said to be delocalized and the molecule is said to be resonance stabilized. |
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Term
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Definition
| A complete structural formula (such as Lewis structure) shows all the atoms and bonds in the molecule. A condensed structural formula shows each central atom along with the atoms bonded to it. A line-angle formula assumes that there is a carbon atom wherever two lines meet or a line begins or ends |
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Term
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Definition
| The number of bonds an atom usually forms. |
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Term
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Definition
| Those electrons that are in the outermost shell. |
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Term
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Definition
| The belief that syntheses of organic compounds require the presence of a "vital force." |
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