Chemistry study notes
Chemical Bonding
Use electrons, molecular shape and electrostatic attraction to explain structures, properties and reactivity.
A-Level 9476 (2026-2027)
Choose a topic
6 topicsWhat holds particles together?
Ionic, covalent, metallic and dative bonding, with complete electron diagrams.
Orbital overlap and molecular shape
Sigma/pi overlap, VSEPR and deductions for unfamiliar molecules.
Bond polarity versus molecular polarity
Electronegativity produces bond dipoles; shape determines their vector sum.
Attractions between particles
Instantaneous and permanent dipoles, hydrogen bonds, ice and water.
Bond length, energy and reaction
Distinguish bond strength from polarity and avoid single-factor reactivity rules.
Identify a structure from its properties
Compare all five required crystalline structures and reason from evidence.
Scope and references
Learning outcomes and sources
2. Chemical Bonding. Use the outcome map to find the explanation for a particular syllabus requirement.
See the learning outcome map
2(a) Explain the electrostatic nature of chemical bonds.
- (i) Oppositely charged ions
- (ii) Shared pair and positive nuclei
- (iii) Positive-ion lattice and delocalised electrons
2(b) Describe bonding with complete electron diagrams.
- (i) NaCl and MgO
- (ii) H2, O2, N2, Cl2, HCl, CO2, CH4 and ethene
- (iii) NH4+ formation and Al2Cl6 dative bonds
All chemical bonds involve attraction between chargesCount shared pairs and every lone pairA dative bond uses two electrons from one donor
2(c) Explain covalent bonds using orbital overlap.
- s and p overlap only
- Sigma and pi bonds
- Connection to organic structures
2(d) Explain required molecular shapes and angles by VSEPR.
- BF3 trigonal planar
- CO2 linear
- CH4 tetrahedral
- NH3 trigonal pyramidal
- H2O bent
- SF6 octahedral
2(e) Predict analogous shapes and angles.
- Electron-region count
- Bond pairs and lone pairs
- Analogous unfamiliar molecules and ions
2(f) Explain bond polarity using electronegativity.
- Qualitative electronegativity
- Partial charges; no numerical electronegativity calculation
2(g) Deduce molecular polarity.
- Bond dipoles
- Three-dimensional molecular shape
- Symmetry and cancellation in analogous shapes
2(h) Explain electrostatic attractions between particles.
- (i) Permanent and induced dipoles: CHCl3(l), Br2(l), liquid noble gases
- (ii) Hydrogen bonding in NH3 and H2O; N-H and O-H groups
2(i) Link hydrogen bonding to physical properties.
- Ice and liquid water
- Density and melting
- Thermal properties and suitable solubility examples
2(j) Define covalent bond energy and length.
- Gas-phase bond breaking per mole
- Mean energy versus a specific bond
- Equilibrium internuclear distance
2(k) Compare bond reactivity using structure.
- Bond energy
- Bond length
- Bond polarity and limits of one-factor predictions
2(l) Describe the required crystal structures.
- (i) Ionic NaCl/MgO
- (ii) Simple molecular iodine
- (iii) Giant molecular diamond/graphite
- (iv) Hydrogen-bonded ice
- (v) Metallic copper
- Unit-cell concepts not required
Different solids contain different moving charges and attractions
2(m) Predict properties from structure and bonding.
- Strength of attractions
- Mobile charge carriers
- State, melting, conductivity, mechanical behaviour and solubility
Different solids contain different moving charges and attractionsUse several observations to identify a structure
2(n) Infer structure and bonding from supplied evidence.
- Use multiple observations
- Distinguish evidence from a unique identification
- State-dependent conductivity
- SEAB H2 Chemistry 9476, examination 2026
Topic 2, printed pages 14-15. All 14 outcomes, named compounds and exclusions inspected. Electron diagrams and examples are original.