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European Baccalaureate Chemistry study materials
European Baccalaureate Chemistry study resources

European Baccalaureate Chemistry: Inorganic and organic chemistry, reaction mechanisms

European Baccalaureate Chemistry · Work through your exam, one topic at a time.

All guide sections

Inorganic and organic chemistry, reaction mechanisms

Inorganic and organic chemistry, including reaction mechanisms, is the largest content area. The exam tests nomenclature, functional groups, isomerism, characteristic reactions and curly-arrow mechanisms, with inorganic periodicity and transition-metal chemistry also appearing.

Core rules

  • Functional groups determine reactivity: alkenes (C=C), alcohols (OH), aldehydes/ketones (C=O), carboxylic acids (COOH), esters (COO), amines (NH2), halogenoalkanes (X).
  • Isomerism includes structural, geometric (E/Z), and optical isomerism (chiral carbon with four different groups). Cis/trans is a special case of E/Z.
  • Key reaction types: electrophilic addition to alkenes, nucleophilic substitution of halogenoalkanes (SN1/SN2), elimination (E1/E2), oxidation of alcohols, esterification, hydrolysis.
  • Mechanism rules: curly arrows show movement of electron pairs from source to sink; SN2 is one step and gives inversion; SN1 proceeds via a carbocation and gives racemisation; tertiary halogenoalkanes favour SN1, primary favour SN2.
  • Markovnikov's rule: in electrophilic addition of HX to an alkene, H adds to the carbon with more hydrogens, giving the more stable carbocation intermediate.
  • Inorganic: period 3 oxides change from basic (Na2O, MgO) through amphoteric (Al2O3) to acidic (SO2, SO3, P4O10). Transition-metal complexes have ligands donating electron pairs; d-orbital splitting explains colour and magnetism.

Worked example

Predict the major product of HBr with propene and explain the mechanism. The alkene attacks HBr; H+ adds to the terminal CH2 carbon so that the positive charge forms on the middle carbon, a secondary carbocation, rather than on a primary carbon. Br− then attacks the carbocation, giving 2-bromopropane. This is electrophilic addition and follows Markovnikov's rule because the more stable carbocation is formed.

Traps that cost marks

  • Drawing curly arrows from atoms rather than from bonds or lone pairs.
  • Saying SN1 is favoured for primary halogenoalkanes; it is favoured for tertiary.
  • Forgetting that oxidation of a primary alcohol can stop at the aldehyde or continue to the carboxylic acid.
  • Writing E/Z when two identical groups are on one carbon; geometric isomerism requires different groups.
  • Confusing ligand substitution with redox in transition-metal complexes.