ChemistryQ&A by dot point

The trend in atomic radius, first ionisation energy and melting point down Group 2. The reactions of Group 2 elements with water. The trend in solubility of the hydroxides and sulfates of Group 2 elements. Uses of magnesium in the extraction of titanium, of calcium hydroxide in agriculture, of barium sulfate in medicine and of Group 2 compounds in neutralising acidity.

The trends in electronegativity and boiling point of the halogens. The trend in oxidising ability of the halogens down the group, including displacement reactions of halide ions in aqueous solution. The trend in reducing ability of the halide ions, including the reactions of solid sodium halides with concentrated sulfuric acid. The use of acidified silver nitrate to identify and distinguish halide ions, and the use of chlorine in water treatment.

The reactions of the Period 3 elements sodium and magnesium with water. The reactions of the Period 3 elements with oxygen to form oxides. The structure and bonding of the Period 3 oxides and the trends in their melting points. The reactions of the oxides with water and the acid-base nature of the resulting solutions. The behaviour of the oxides as acids or bases in their reactions with acids and bases.

The classification of an element as s, p, d or f block according to its outer electron configuration. Trends in atomic radius and first ionisation energy across Period 3 and down a group, explained by nuclear charge, shielding and atomic radius. The trend in melting point across Period 2 and Period 3, explained by the structure and bonding of the elements.

The acidity of metal-aqua ions in terms of the charge density of the metal ion and the polarisation of coordinated water. The reactions of metal-aqua ions with bases such as sodium hydroxide and ammonia, and with carbonate ions. The amphoteric character of the aluminium hydroxide complex. The use of these reactions to identify metal ions in solution by the colours and behaviour of the precipitates formed.

The definition of a transition metal in terms of an incomplete d sub-shell. The characteristic properties of transition metals: complex formation, coloured ions, variable oxidation states and catalytic activity. The shapes of complex ions and the meaning of coordination number and ligand. Stereoisomerism in complexes. Ligand substitution reactions and the chelate effect. The origin of colour in transition metal ions and its use in colorimetry. The role of transition metals as homogeneous and heterogeneous catalysts.

Alcohols as products of fermentation and hydration of alkenes. Classification as primary, secondary and tertiary. Oxidation of alcohols with acidified potassium dichromate(VI) to aldehydes, carboxylic acids and ketones. Elimination to form alkenes. The biofuel debate.

Aldehydes and ketones as carbonyl compounds. Oxidation of aldehydes to carboxylic acids and the use of Tollens' and Fehling's reagents to distinguish them from ketones. Reduction with NaBH4 to alcohols. Nucleophilic addition of HCN to form hydroxynitriles and the production of a racemic mixture.

Alkanes as saturated hydrocarbons from crude oil, fractional distillation, cracking. Combustion of alkanes and the formation of pollutants. Free-radical substitution of alkanes by halogens, including initiation, propagation and termination.

Alkenes as unsaturated hydrocarbons containing a C=C double bond. The bonding in a double bond as a pi bond. Electrophilic addition of alkenes with hydrogen halides, sulfuric acid and bromine. Markownikoff addition and carbocation stability. Addition polymerisation.

Amines as bases and nucleophiles. Preparation of aliphatic amines by reaction of halogenoalkanes with ammonia and by reduction of nitriles. Preparation of aromatic amines by reduction of nitro compounds. The relative base strength of ammonia, primary aliphatic and aromatic amines. Amines as nucleophiles in further substitution.

Amino acids as compounds with both amine and carboxylic acid groups and their behaviour as zwitterions. Formation of proteins by condensation of amino acids and their hydrolysis. The structure of DNA nucleotides, base pairing by hydrogen bonding, and the action of cisplatin. Enzymes as biological catalysts with stereospecific active sites.

The structure of benzene and the delocalised model. Evidence for delocalisation from enthalpies of hydrogenation and bond lengths. Electrophilic substitution reactions of benzene, including nitration and Friedel-Crafts acylation, with mechanisms and the role of the catalyst.

Carboxylic acids as weak acids that react with carbonates. Esterification of carboxylic acids with alcohols and the uses and hydrolysis of esters. Acylation by acyl chlorides and acid anhydrides reacting with water, alcohols, ammonia and amines. The industrial advantages of using acid anhydrides.

Chromatography as a method of separation using a stationary and a mobile phase. Thin-layer and column chromatography and the calculation of Rf values. Gas chromatography and the meaning of retention time. The combination of gas chromatography with mass spectrometry for identification.

Nucleophilic substitution of halogenoalkanes by hydroxide, cyanide and ammonia. Elimination of halogenoalkanes to form alkenes. The effect of bond enthalpy on rate of hydrolysis. CFCs and the depletion of the ozone layer.

Nomenclature, functional groups and homologous series. Structural, displayed, skeletal and molecular formulae. Structural isomers, E-Z stereoisomers and the use of CIP priority. Reaction mechanisms, free radicals, nucleophiles and electrophiles, and curly arrows.

The use of carbon-13 and proton (high-resolution) NMR spectroscopy. The number of peaks and chemical shift indicating different environments. Integration giving the ratio of hydrogen atoms. Spin-spin splitting interpreted with the n+1 rule, and the use of TMS as a reference and deuterated solvents.

Optical isomerism as a form of stereoisomerism. The chiral centre and its four different groups. Optical isomers (enantiomers) as non-superimposable mirror images. The effect of enantiomers on plane-polarised light and the meaning of a racemic mixture.

Tests for alkenes, alcohols, aldehydes and carboxylic acids. Use of bromine water, acidified potassium dichromate(VI), Fehling's and Tollens' reagents, and sodium carbonate. Determination of empirical and molecular formulae from combustion or composition data. The principle of mass spectrometry and infrared spectroscopy for structure determination.

Synthetic routes for preparing one organic compound from another in several steps. Reagents and conditions for the interconversion of functional groups in aliphatic and aromatic chemistry. Practical techniques for organic preparation, including purification and the determination of percentage yield.

Addition polymers from alkenes. Condensation polymers, including polyesters and polyamides, from two monomers or one monomer with two functional groups. Identifying the repeating unit and the monomers. Hydrolysis of condensation polymers. Biodegradability and disposal of polymers.

Bronsted-Lowry acids and bases, the pH scale and calculating pH of strong acids, the ionic product of water Kw, weak acids and Ka, pH curves and titrations, and buffer action.

The Avogadro constant and the mole, the ideal gas equation, empirical and molecular formulae, balanced equations and associated calculations, percentage yields and atom economy, and concentrations of solutions.

Fundamental particles (protons, neutrons, electrons), mass number and atomic number, isotopes, the time of flight (TOF) mass spectrometer, relative atomic mass, electron configuration in sub-shells, and the trends in ionisation energy across periods and down groups.

Ionic, covalent, dative covalent and metallic bonding, the four crystal structures, electron pair repulsion theory and molecular shapes, bond polarity and electronegativity, and the forces between molecules including van der Waals, dipole-dipole and hydrogen bonding.

Dynamic equilibrium, Le Chatelier's principle and the effect of changing concentration, pressure and temperature, the role of a catalyst, and the equilibrium constant Kc and its calculation.

Electrode potentials and the standard hydrogen electrode, electrochemical cells and cell EMF, using standard electrode potentials to predict feasibility, and commercial cells and fuel cells.

Enthalpy change, exothermic and endothermic reactions, standard enthalpy changes (formation, combustion), calorimetry and the equation q = mcDeltaT, Hess's law and enthalpy cycles, mean bond enthalpies.

Mole fractions and partial pressures, the equilibrium constant Kp written in terms of partial pressures, calculating Kp, and the effect of changing conditions on Kp.

Collision theory, the Maxwell-Boltzmann distribution, the effect of temperature, concentration, pressure, surface area and catalysts on rate, and how catalysts lower activation energy.

Oxidation states (rules for assigning them), oxidation as loss of electrons and reduction as gain, oxidising and reducing agents, and writing and balancing half-equations and overall redox equations.

Rate equations, orders of reaction and the rate constant k, determining orders from initial-rate and concentration-time data, the Arrhenius equation, and using the rate-determining step to deduce a mechanism.

Born-Haber cycles and lattice enthalpies, enthalpies of solution and hydration, entropy change, and Gibbs free energy DeltaG = DeltaH - T DeltaS as the test of feasibility.