Organichemica
Basic Organic Chemistry

A Tutorial

Dave Woodcock ©2001

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Level 1

Glossary

S

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sigma (s) bond

A bond formed by the overlap of atomic orbitals symmetrical about the bond axis this making the bond symmetrical about the bond axis. This symmetry explains the ability of the atoms linked by it to freely rotate.
Sigma bonds are formed by interacting s, p (head on), sp, sp2 and sp3 atomic orbitals.

solubility

The property of one compound mixing with another.
Compounds which completely mix with each other are said to be miscible.
When compounds are not miscible, solubility is often measured in g solute/100 mL solvent

solute

The compound which is being dissolved in the solvent

solvent

Chemical reactions require that the molecules of the reactants meet before the reaction can take place. The solvent is a liquid (usually) which dissolves the reactants (the solute allowing them to react.
Solvents, as a rule, must be inert to the reactants and products in the reaction. Sometimes it is possible to use one of the reactants as the solvent when the term solvolysis may be used.

solvolysis

A term meaning that the solvent is one of the reactants. When the solvent is water, the term hydrolysis is used.

sp hybridization

A recalculation of the atomic orbitals for the outer shell of electrons in which the ground state electronic structure (s, p, p, p) is converted into the excited state electronic structure (sp, sp, p, p).
sp atomic orbitals are obtained by combining the original s with one p orbital to produce two sp hybridized orbitals.

sp2 hybridization

A recalculation of the atomic orbitals for the outer shell of electrons in which the ground state electronic structure (s, p, p, p) is converted into the excited state electronic structure (sp2, sp2, sp2, p).
sp2 atomic orbitals are obtained by combining the original s with two p orbitals to produce three sp2 hybridized orbitals.

sp3 hybridization

A recalculation of the atomic orbitals for the outer shell of electrons in which the ground state electronic structure (s, p, p, p) is converted into the excited state electronic structure (sp3, sp3, sp3, sp3).
sp2 atomic orbitals are obtained by combining the original s with three p orbitals to produce four sp3 hybridized orbitals.

spacefill option, chime

Obtained by right clicking on the model to obtain a menu, then clicking on Display, Spacefill, van der Waals, successively.

step, stepwise mechanism

step: A chemical reaction which shows the reactants and products produced in a single collision.
stepwise mechanism: A series of sequential steps by which the reactants are converted into products. The sum of the steps in the stepwise series will be the overall chemical equation for the reaction.

stereogenic centre

See chirality centre.

stereoisomer

Isomers which have the same bonding order and which differ from each other only in the spacial distribution of the groups (atoms) are called stereoisomers.
A pair of stereoisomers which are mirror images of each other are termed enantiomers.
Stereoisomers which are not mirror images of each other are termed diastereoisomers.

stereoselective

If the mechanism of a chemical reaction does not dictate the stereoisomeric outcome of the reaction, and yet one stereoisomer is favoured over another by some other feature of the reaction, the reaction is stereoselective. This is the case even if the selectivity is 100% of one stereoisomer.
See stereospecific

stereospecific

If a reaction produces a specific stereoisomeric product as a result of a reaction mechanism by which other stereoisomers cannot be produced, the reaction is stereospecific.
See stereoselective

stereochemistry

The specific spacial orientation of the atoms within a molecule.

steric

Steric effects are the result of the physical bulk of a non-reacting part of a molecule on the reaction site. Large, bulky groups near a rection site will slow access to that site by a reacting species, and so will slow the reaction step.

substrate

The compound which is to undergo a chemical change when acted upon by reagents.

syn addition

An addition process whereby the two species adding do so on the same side of the multiple bond being added to.

synthesis

A chemical reaction, or a reaction sequence, whereby a particular compound might be made from other compounds.

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