Organichemica
Basic Organic Chemistry

A Tutorial

Dave Woodcock ©2001OUC Home Page Chem Home Page

Level 1

Glossary

A

Main Index
Glossary Index


a-

A negation as in achiral (not chiral), acyclic (not cyclic), asymmetric (not symmetric).

absolute configuration

The actual spacial orientation of the atoms in a molecule.

acetal/ketal

A functional group with two alkoxy groups attached to one carbon, R2C(OR')2.
If one of the R groups is a hydrogen atom, acetal is correct. If neither of the R groups is hydrogen, ketal is correct. However, acetal is commonly used for both types.

achiral

A species which has a mirror-image identical to itself, that is, the species and its mirror image are superposable.

acid

Brønsted: an H+ donor.
Lewis: an electron pair acceptor in bond formation.

acid dissociation

The reaction in which a Brønsted acid donates a proton to water:
In this relationship the a-values on the right hand side refer to activities, which, for dilute solutions, and so for most practical purposes, are equal to the concentrations (moles/L) of the various species but without the units.

activating group

A group in a molecule which has the property of increasing the rate of reaction at another site in that molecule.

activation energy

Ea. The minimum excess energy required by a reaction; a reaction cannot occur unless the activation energy is available.

activity

Thermodynamically, equilibrium constants are expressed in terms of activities and not concentrations. A brief introduction to university-level thermodynamics and equilibrium is available on this site.
For an organic course, it is likely sufficient to remember that for dilute solutions the activity and the concentration of the solution (in moles/L) are numerically equal, the difference being that the activity has no units. For the same dilute solutions, the activity of the solvent is taken to be 1 (no units).

acyclic

A non-cyclic molecule.

acyl

The group RCO-, most usually attached to an atom having a lone pair of electrons, but not necessarily so.

acylation

A reaction involving the transfer of an acyl group.

addition

A reaction involving the addition of a reagent across a p bond or bonds such that a part of the reagent adds to each end of the bond(s). 1,2-addition refers to addition across one p bond; 1,4-addition refers to addition to the two atoms at the end of a chain of two conjugated p bonds.

alcohol

1. A common name used for the alkanol (R-OH, R = alkyl) functional group.
2. A common name for the compound ethanol, C2H5OH.

alkaloid

A naturally occurring compound containing nitrogen.

alkane
The family name for the compounds of formula CnH2n+2.
The compounds contain only carbon and hydrogen linked only by single (2 electron) bonds.
Examples:
Name
Formula
Model
methane
CH4
ethane
C2H6
propane
C3H8

alkanol

The family of compounds containing the R-OH group.

alkoxy

A carbon chain attached to another group through an oxygen atom, RO-.

alkyl

Any chain of singly bonded carbon atoms, often designated R- in formulae. R-may also be a hydrogen atom.

alkyl halide

A common name for the haloalkane family, R-Cl.

anion

A negatively charged atom or group of atoms. If the electron excess is at carbon, the species is termed a carbanion.
Anions are often nucleophiles in organic reactions.

anti addition

In anti addition the two atoms or groups adding come in from opposite sides of the double bond.

asymmetric centre

See chirality centre.

atom

The smallest portion of matter which can show the chemical properties of an element. Consists of an extremely small nucleus made up of positively charged protons and neutral neutrons, surrounded by negatively charged electrons in sufficient number to give a neutral atom. It is the number of protons in the nucleus which dictates the number of electrons in the neutral atom and this in its turn dictates the chemistry.

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Main Index

page upkeep: Dave.
I would appreciate comments and additions by email to:
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