Capstone: Structure decides properties
One idea runs through the whole of C2: a substance's structure and bonding decide its properties. Sort each substance into the structure type its properties point to — ionic, simple molecular, giant covalent or metallic.
Drag each substance into a box — or tap it to step through the boxes. Then press Check.
Ionichigh m.p.; conducts molten/dissolved
Simple molecularlow m.p.; does not conduct
Giant covalentvery high m.p.; very hard
Metallicconducts; malleable
📋 C2 Bonding, Structure & Properties — Quick-Reference Summary
- Solids: fixed shape, fixed volume, close-packed regular particles. Liquids: fixed volume, flow, close irregular particles. Gases: no fixed shape/volume, compressible, widely spaced particles.
- Changes of state are physical and reversible. Temperature stays constant during melting and boiling — energy breaks forces, not raises temperature.
- Ionic bonding: metal transfers electrons to non-metal → oppositely charged ions → electrostatic attraction. Ionic compounds form giant ionic lattices with high MP. Conduct only when molten or dissolved (ions free to move).
- Covalent bond = shared pair of electrons. Occurs between non-metals. Single (1 pair), double (2 pairs), triple (3 pairs).
- Simple molecules: low MP/BP (weak intermolecular forces — not weak bonds). Do not conduct electricity. N.B. covalent bonds themselves are strong.
- Giant covalent structures: many strong covalent bonds → very high MP, very hard, insoluble. Examples: diamond, graphite, SiO2.
- Diamond: 4 bonds per C, 3D network, hardest natural substance, does not conduct. Graphite: 3 bonds per C, layered, soft/slippery, conducts electricity (delocalised e⁻).
- Graphene: one layer of graphite — strong, lightweight, conducts. Nanotubes: cylindrical fullerenes with very high length:diameter ratio — strong, conducts. C60: simple molecule, hollow sphere, drug delivery.
- Metallic bonding: lattice of positive ions + sea of delocalised electrons. Explains conductivity (e⁻ free to move), malleability (layers slide), high MP (strong attraction).
- Alloys: different-sized atoms distort layers → harder than pure metal. (Beyond the syllabus: shape memory alloys such as Nitinol return to their original shape on heating.)
- Nanoparticles T: diameter 1–100 nm. SA:V ratio increases by factor of 10 for every factor of 10 decrease in particle size. Properties differ from bulk material. Uses: medicine, electronics, cosmetics/sun creams, deodorants, catalysts. Risks: unknown long-term health/environmental effects.
That completes C2. It builds directly on the electronic structure of C1 — Atomic Structure (which electrons are gained, lost or shared decides the bonding), and it leads into C3 — Quantitative Chemistry, where those same formulae become the basis for working out masses, moles and reacting quantities.