Chap 14 (Introduction to organic chemistry)

Structural formula

The formula that shows how many, and the symbols of atoms bonded to each carbon atom in an organic molecule

Displayed formula

a 2D representation of an organic molecule, showing all its atoms and their bonds

Skeletal formula

A simplified displayed formula with all C and H atoms and C-H bonds removed

Homologous series

a group of organic compounds having the same functional group, the same general formula and similar chemical properties

Functional group

An atom or groups of atoms in an organic molecule which determines the characteristic chemical reaction

General formula

A formula that represents a homologous series of compounds using letters and numbers. E.g. the general formula for alkanes is CnH2n+2

Aliphatic compounds

straight-chain or branched-chain organic compounds, and also include cyclic organic compounds that do not contain benzene rings

Single covalent bond

A bond made up of a pair of electrons shared between two atoms

Sigma bond

A single covalent bond formed by the 'end on' overlap of atomic orbitals

Pi bond

A covalent bond formed by the sideways overlap of p and p, or p and d atomic orbitals

Structural isomers

Compounds with the same molecular formula but different structural formula

Stereoisomers

Compounds whose molecules have the same atoms bonded to each other in the same way, but with a different arrangement of atoms in space so that the molecules cannot be superimposed on each other

Geometrical isomerism

Displayed by unsaturated or ring compounds with the same molecular formula and order of atoms but different shapes. It arises because of a lack of free rotation about a double bond (due to presence of pi bond) or a ring structure

Enantiomers

A pair of optically active molecules whose mirror images cannot be superimposed

Chiral centre

a carbon atom with the four different atoms or groups of atoms attached. This allows optical isomers to exist

Reaction mechanism

The series of steps that take place in the course of the overall reaction

Free-radical reaction

a "three-step' reaction that starts with the production of reactive atoms or molecules with an unpaired electron. The second step regenerates free radicals. Then the reaction finishes with two free radicals meeting to form a molecule

Carbocation

An alkyl group with a single positive charge on one of its carbon atoms. It is formed in reaction mechanisms, e.g. CH3+

Electron deficient

an atom or molecule that has less than its usual share of electrons

Inductive effect

The uneven sharing of electrons along a covalent bond. Electron-donating species, such as an alkyl group, are said to have a positive inductive effect, whereas electron-withdrawing species, such as an oxygen atom, have a negative inductive effect.

Electrophile

A species in organic chemistry that can act as an electron pair acceptor

Nucleophile

Species that can act as a donor of a pair of electrons

Addition reaction

An organic reaction in which two or more molecules combine to give a single product molecule

Elimination reaction

a reaction in which a small molecule, such as H2O or HCl, is removed from an organic molecule.

Condensation reaction

A reaction in which two organic molecules join together and in the process, eliminate a small molecule such as water or hydrogen chloride

Substitution reaction

a reaction that involves the replacement of one atom, or group of atoms, by another

Oxidation reaction

The addition of oxygen, removal of electrons or increase in oxidation number of a substance ; in organic chemistry this refers to a reaction in which oxygen atoms are added to a molecule and/or hydrogen atoms are removed from a molecule

Reduction reaction

The removal of oxygen, addition of electrons or decrease in oxidation number of a substance ; in organic chemistry it is the removal of oxygen atoms from a molecule and/or the addition of hydrogen atoms to a molecule

Free-radical substitution

the reaction in which halogen atoms substitute for hydrogen atoms in alkanes. The mechanism involves steps in which reactive free radicals are produced (initiation), regenerated (propagation) and consumed (termination).