Organichemica
Basic Organic Chemistry

A Tutorial

Dave Woodcock ©2001

OUC Home Page Chem Home Page
Level 1

Glossary

E

Main Index
Glossary Index


electron deficient/electron poor

An atom in a molecule or ion which is deficient in electrons: an atom that can add electrons. For boron and carbon atoms, this means the lack of an octet of electrons. Such a species is often termed an electrophile.

electronegativity

the ability of an atom to pull electrons towards itself and away from another atom it is bonded to.
If the periodic table is considered to be a rectangle, then electronegativity increases from bottom left to top right (excluding the noble gases). Thus F is the most electronegative atom.

electronic requirements

A particular reaction site may be electron rich, electron poor, or electron neutral. A reagent attacking the reaction site usually must be the opposite in electron requirements, such that an electron rich reactant site will need an electron poor reactant, etc.
An electron rich reactant is often called a nucleophile.
An electron poor reactant is often called an electrophile.

electronic geometry (shape)

This the shape due to the distribution in space of all electron groupings (bond groups and lone pairs) around an atom. This differs from the molecular geometry (shape) in that this latter includes only bonded electrons and does not include lone pairs of electrons.
Thus, if an atom has a total of four electron groups around it, the electronic geometry is tetrahedral. If two of these groups are lone pairs of electrons, the the molecular geometry is due only to the two bond groups, and the molecular geometry is bent (or angular).

electron rich

An atom in a molecule or ion which has electrons available and which it can donate in reaction. Such a species is often termed a nucleophile.
An electron rich site may be due to an excess of electrons (an anion) or to the presence of a lone pair, or other electrons (such as p electrons), available for donation to an electron poor site.

electron wave

A mathematical description for the electron in an atom, made necessary because of the situation described by the Heisenberg Uncertainty Principle.

electrophile

An electron deficient species; an electron seeking species.
Examples of electrophiles are: H in molecules polarizing to H+ (e.g. HCl); Boron in (e.g.) BH3.

electrophilic addition

An electron deficient species (an electrophile) forms a new bond to an electron rich species.
Examples of electrophiles are: H in molecules polarizing to H+ (e.g. HCl); Boron in (e.g.) BH3.
This usually forms a cation; if the cation is a carbocation (as in electrophilic addition to a C=C bond) a second addition -- this time of a nucleophile -- may occur.

enantiomers

A pair of stereoisomers which are mirror images of each other are termed enantiomers.

excited state

Any state of the atom or molecule that has more energy than the minimum possible energy (found in the ground state)

Glossary Index
A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z


Main Index

page upkeep: Dave.
I would appreciate comments and additions by email to:
woodcock@okanagan.bc.ca
This page last modified on: