| A | B | C | D | E | F | G | H | I | K, L | M | N | O | P, Q | R | S | T | U, V, W , Y | |
|
GlossaryThis glossary is intended to offer help in crossing disciplinary boundaries, especially for those beginning to explore the terminology-rich field of chemistry. The entries are neither exhaustive in scope nor definitional in quality. A small fraction of the entries define terms introduced in the present work. Cross-references are marked as links (for example, abstraction reaction); an alphabetical search will occasionally yield a different form of the indicated word. Some words in the main text are marked in the same way. |
|
| Abstraction reaction | A reaction that removes an atom from a structure. |
| Acid | In the Brønsted definition, an acid is a chemical species that can donate a proton to another species (a base). In the Lewis definition, an acid is a chemical species that can accept (and share) a pair of electrons from another species. Hydrochloric acid is a Brønsted acid; the proton it donates is a Lewis acid. A neutral Lewis acid and a neutral Lewis base can commonly form a dipolar bond. |
| Activation energy | Distinct states correspond to minima of a potential energy surface in a configuration space. In this classical picture, the activation energy for transforming state A into state B is the maximum increase in energy (relative to the ground state of A) encountered on a minimum-energy path from A to B. Energy here refers to potential energy; an analogous definition based on free energy can be constructed. When tunneling is considered, lower energy paths become possible, but an activation energy can be associated with the reaction (at a given temperature) via the relationship between temperature and reaction rate. |
| Acyclic | Not cyclic. |
| Affinity constant | The reciprocal of the dissociation constant; a measure of the binding energy of a ligand in a receptor. |
| AFM | An atomic force microscope. |
| Alkane | A saturated, acyclic hydrocarbon structure; usually quite inert. |
| Alkene | A hydrocarbon containing a double bond; often rather reactive. |
| Alkyne | A hydrocarbon containing a triple bond; often rather reactive. |
| Amide | A molecule containing an amine bonded to a carboxyl group; the resulting bond has substantial double-bond character. Also termed a peptide; amide bonds link amino acids in proteins. |
| Amine | A molecule containing N with a single bond to C and two other single bonds to H or C (but not an amide); the amine group or moiety. |
| Amino acid | A molecule containing both an amine and a carboxylic acid group; in the 20 genetically encoded amino acids in biology, both groups are bound to the same C. Amino acids joined by amide bonds form peptides and proteins; these do not contain amino acids as such, and are instead said to contain amino acid residues. |
| Anion | A negatively charged ion. |
| Aromatic | A term used to describe cyclic pi-bonded structures of special stability. |
| Assembler | In recent popular usage, any nanomachine, usually assumed to offer magical, universal capabilities in an atom-sized package. In the author's usage, any programmable nanomechanical system able to perform a wide range of mechanosynthetic operations. See molecular manipulator, molecular mill. |
| Atomic force microscope | A device in which the deflection of a sharp stylus mounted on a soft spring is monitored as the stylus is moved across a surface. If the deflection is kept constant by moving the surface up and down by measured increments, the result (under favorable conditions) is an atomic-resolution topographic map of the surface. Also termed a scanning force microscope. |
Copyright © 1998 by John Wiley & Sons, Inc.
