IB Chemistry home > Syllabus 2016 > Organic chemistry: 10.10 - Organic structure and formula

Syllabus ref: 10.1

Organic compounds are compounds of carbon that originally were thought to only be derived from living systems. Nowadays we know that this is not exclusively the case, and the definition is extended to include any compound of carbon not generally considered to be inorganic, such as the simple oxides or carbonates.

Nature of science:

Serendipity and scientific discoveries: PTFE and superglue.

Ethical implications: drugs, additives and pesticides can have harmful effects on both people and the environment.

Transdisciplinary: the three-dimensional shape of an organic molecule is the foundation pillar of its structure and often its properties. Much of the human body is chiral.

Understandings

Essential idea: Organic chemistry focuses on the chemistry of compounds containing carbon.

A homologous series is a series of compounds of the same family, with the same general formula, which differ from each other by a common structural unit.

Structural formulas can be represented in full and condensed format.

Structural isomers are compounds with the same molecular formula but different arrangements of atoms

Functional groups are the reactive parts of molecules.

Saturated compounds contain single bonds only and unsaturated compounds contain double or triple bonds.

Benzene is an aromatic, unsaturated hydrocarbon.

Understandings - HL

Essential idea: Stereoisomerism involves isomers which have different arrangements of atoms in space but do not differ in connectivity or bond multiplicity (ie whether single, double or triple) between the isomers themselves

Stereoisomers are subdivided into two classes-conformational isomers, which interconvert by rotation about a s bond and configurational isomers that interconvert only by breaking and reforming a bond. Configurational isomers are further subdivided into cis-trans and E/Z isomersand optical isomers.

Cis-trans isomers can occur in alkenes or cycloalkanes (or heteroanalogues) and differ in the positions of atoms (or groups) relative to a reference plane.According to IUPAC, E/Z isomers refer to alkenes of the form R1R2C=CR3R4 (R1 ≠ R2, R3 ≠ R4) where neither R1 nor R2 need be different from R3 or R4.

A chiral carbon is a carbon joined to four different atoms or groups.

An optically active compound can rotate the plane of polarized light as it passes through a solution of the compound. Optical isomers are enantiomers. Enantiomers are non-superimposeable mirror images of each other. Diastereomers are not mirror images of each other.

A racemic mixture (or racemate) is a mixture of two enantiomers in equal amounts and is optically inactive.

Applications and skills

Explanation of the trends in boiling points of members of a homologous series.

Distinction between empirical, molecular and structural formulas.

Identification of different classes: alkanes, alkenes, alkynes, halogenoalkanes, alcohols, ethers, aldehydes, ketones, esters, carboxylic acids, amines, amides,nitriles and arenes.

Identification of typical functional groups in molecules eg phenyl, hydroxyl, carbonyl, carboxyl, carboxamide, aldehyde, ester, ether, amine, nitrile, alkyl, alkenyl and alkynyl.

Construction of 3-D models (real or virtual) of organic molecules.

Application of IUPAC rules in the nomenclature of straight-chain and branched-chain isomers.

Identification of primary, secondary and tertiary carbon atoms in halogenoalkanes and alcohols and primary, secondary and tertiary nitrogen atoms in amines.

Discussion of the structure of benzene using physical and chemical evidence.

Applications and skills - HL

Construction of 3-D models (real or virtual) of a wide range of stereoisomers.

Explanation of stereoisomerism in non-cyclic alkenes and C3 and C4 cycloalkanes.

Comparison between the physical and chemical properties of enantiomers.

Description and explanation of optical isomers in simple organic molecules.

Distinction between optical isomers using a polarimeter.

In Chapter 10.1