Structure 2. Models of bonding and structure

2.1.1Ion formation

• Metal atoms lose electrons → cations (+) • Non-metal atoms gain electrons → anions (−) • Predict ion charges from electron configurations

2.1.2Ionic bonding

• Electrostatic attraction between oppositely charged ions • Binary ionic compounds: cation first, anion with "-ide" suffix • Deduce formulas and names of ionic compounds, including common polyatomic ions

2.1.3Ionic compounds

• 3D lattice structures, empirical formulas • Properties: volatility, electrical conductivity, solubility • Explain properties using lattice structure and ion mobility

• Electrostatic attraction between shared electron pair and nuclei • Octet rule: tendency to achieve 8 valence electrons • Lewis formulas (up to 4 electron pairs per atom)

• Single, double, triple bonds (1, 2, 3 shared pairs) • More bonds → shorter length, stronger bond

• Both electrons from same atom • Identify coordination bonds; include transition element complexes at HL

• Predict molecular shapes from electron domain repulsion • Electron domain and molecular geometry (up to 4 domains) • Include bond angles and lone-pair effects for common shapes

• Results from electronegativity differences • Deduce polar bonds from electronegativity values and show bond dipoles

• Depends on bond polarity + molecular geometry • Net dipole moment • Identify when bond dipoles cancel or produce a polar molecule/ion

• Carbon allotropes: diamond, graphite, fullerenes, graphene • Silicon and silicon dioxide

• London dispersion forces • Dipole-induced dipole • Dipole-dipole • Hydrogen bonding • Deduce IMF types from molecular size and polarity

• Relative strength: London < dipole-dipole < hydrogen bonding • Effects on volatility, conductivity, solubility • Explain properties of covalent substances using IMF strength and molar mass

• Separates components based on IMF attractions • Calculate and interpret RF values • Link mobile/stationary phase attraction to separation; operational details are not assessed

• Multiple possible positions for double bonds • Deduce resonance structures and use the term delocalization

• Important resonance example

• Atoms with 5 or 6 electron domains • VSEPR for these species • Draw Lewis formulas and geometries for five- and six-domain species

• Determine preferred Lewis formula • Use formal charge to compare valid Lewis structures

• σ bonds: head-on orbital combination, electron density along bond axis • π bonds: lateral p-orbital combination, electron density on opposite sides

• Mixing atomic orbitals to form hybrid orbitals • Relationships: Lewis formulas → electron domains → geometry → hybridization • Analyse hybridization and bond formation in molecules and ions

• Electrostatic attraction between cation lattice and delocalized electrons • Properties: electrical/thermal conductivity, malleability

• Depends on ion charge and metal ion radius • Trends in melting points (s and p block metals)

• Delocalized d-electrons • High melting points, electrical conductivity

• Ionic ↔ covalent ↔ metallic • Bonding triangle representation

• Position determined by relative contributions of three bonding types • Predict properties from position • Use electronegativity data to place compounds in the bonding triangle

• Mixtures of metals with enhanced properties • Non-directional bonding

• Macromolecules from repeating monomers • Properties of plastics

• Form by breaking double bonds in monomers • Represent repeating units from given alkene monomers

• Form with release of small molecule • Polyamides and polyesters • Represent repeating units from given difunctional monomers