§-Unit

Unit 1: Chemical fundamentals (structure, properties and reactions)

8 dot points, in syllabus order. Each dot point has a focused answer, with exam-style questions and worked answers where available.

Topic 1: Properties and structure of atoms

Describe electron configuration in terms of shells, subshells (s, p, d) and orbitals using the (1s 2s 2p 3s 3p 4s 3d 4p) filling order, and explain the periodic trends in atomic radius, first ionisation energy and electronegativity using effective nuclear charge and shielding

Electron configuration and periodic trends. Walks through the s, p and d subshell filling order using the aufbau principle, Pauli exclusion and Hund's rule, then explains atomic radius, first ionisation energy and electronegativity in terms of effective nuclear charge and shielding.

11 min read →

Describe the nuclear model of the atom in terms of protons, neutrons and electrons; use nuclear notation and define isotopes; calculate relative atomic mass from isotopic composition determined by mass spectrometry

Atomic structure. Defines protons, neutrons and electrons in the nuclear model, walks through nuclear notation and isotopes, and shows the weighted-mean calculation of relative atomic mass from mass spectrometry abundances.

10 min read →

Topic 2: Properties and structure of materials

Identify the three classes of intermolecular force (dispersion forces, dipole-dipole forces, hydrogen bonding) and use them to explain the physical properties of covalent molecular substances (melting and boiling points, solubility, viscosity, surface tension)

Intermolecular forces. Distinguishes dispersion forces, dipole-dipole attractions, and hydrogen bonding by origin and relative strength, then uses them to explain melting and boiling points, solubility, viscosity and surface tension of covalent molecular substances.

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Describe covalent bonding as the sharing of electron pairs between non-metal atoms, draw Lewis structures for simple molecules and polyatomic ions, predict molecular shape using VSEPR theory, and determine bond polarity and overall molecular polarity from electronegativity differences and geometry

Covalent bonding. Walks through drawing Lewis structures for molecules and polyatomic ions, predicts shapes (linear, bent, trigonal planar, trigonal pyramidal, tetrahedral) using VSEPR theory, and determines bond and overall molecular polarity from electronegativity differences and the symmetry of the structure.

11 min read →

Describe ionic bonding as the electrostatic attraction between oppositely charged ions in a regular three-dimensional lattice, predict the formula of binary ionic compounds, and relate physical properties (melting point, electrical conductivity, brittleness, solubility) to lattice structure

Ionic bonding. Explains how electron transfer forms cations and anions held in a 3D lattice by electrostatic attraction, predicts formulae for binary ionic compounds, and links lattice structure to the high melting point, brittleness, conductivity only when molten or dissolved, and variable solubility of ionic substances.

10 min read →

Describe metallic bonding as the electrostatic attraction between a lattice of metal cations and a sea of delocalised valence electrons, and explain the characteristic properties of metals (electrical and thermal conductivity, malleability, ductility, lustre, variable melting point) in terms of this model

Metallic bonding. Describes the cation-and-delocalised-electron model, then explains the characteristic properties of metals (electrical and thermal conductivity, malleability, ductility, lustre, variable melting point) in terms of mobile electrons and the way the lattice deforms under stress.

9 min read →

Topic 3: Chemical reactions (reactants, products and energy change)

Distinguish exothermic and endothermic reactions; represent energy changes using enthalpy values (Delta H) and energy profile diagrams; calculate heat changes (q = mcDeltaT) from calorimetry data and use molar enthalpy of reaction (kJ/mol) in stoichiometric problems

Energy in chemical reactions. Distinguishes exothermic (negative Delta H) and endothermic (positive Delta H) reactions, draws energy profile diagrams with activation energy, and uses calorimetry data with q = mcDeltaT to calculate molar enthalpy of reaction.

11 min read →

Apply the mole concept to chemical reactions: convert between mass, moles, particles, gas volumes (at STP) and solution concentration; use stoichiometric ratios from a balanced equation to determine limiting reagent, theoretical yield and percentage yield

Mole concept. Converts between mass, moles, particles, gas volumes (at STP and SLC) and solution concentration; uses balanced-equation stoichiometric ratios to determine limiting reagent, theoretical yield and percentage yield.

11 min read →