C2 Flashcards
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Define ionic bonding.
Transfer of electrons from a metal to a non-metal, forming oppositely charged ions (e.g., Na⁺Cl⁻).
Example of an ionic compound.
Sodium chloride (NaCl).
Draw a dot-and-cross diagram for NaCl.
Na donates 1 electron to Cl: Na⁺ [ ] and Cl⁻ [•].
Why do ionic compounds have high melting points?
Strong electrostatic forces between ions require lots of energy to break.
Do ionic compounds conduct electricity?
Only when molten/dissolved (ions free to move).
Define covalent bonding.
Sharing electrons between non-metals (e.g., H₂O, CO₂).
Example of a simple covalent molecule.
Water (H₂O).
What is a giant covalent structure?
Atoms bonded in a lattice (e.g., diamond, graphite).
Properties of simple covalent molecules.
Low melting points (weak intermolecular forces), poor conductivity.
Why does graphite conduct electricity?
Delocalized electrons between layers.
Define metallic bonding.
Lattice of positive ions in a sea of delocalized electrons.
Why are metals malleable?
Layers of ions can slide over each other.
What are alloys?
Mixtures of metals with different-sized atoms, disrupting layers and increasing hardness.
States of matter: solid vs liquid vs gas.
Solid (fixed shape), liquid (flows), gas (fills container). Energy increases from solid → gas.
Why do substances melt?
Energy overcomes forces between particles, allowing movement.
Compare ionic vs covalent bonding.
Ionic: electron transfer, metals + non-metals. Covalent: electron sharing, non-metals only.
Structure of diamond.
Giant covalent lattice; each C bonded to 4 others (hard, high melting point).
Structure of graphene.
Single layer of graphite; hexagonal carbon lattice (conducts, strong).
Uses of fullerenes.
Drug delivery, catalysts, nanotechnology.
Define a polymer.
Long chains of repeating covalent monomers (strong intermolecular forces).
Properties of polymers.
Flexible, high melting points (varies with chain length).
What are nanoparticles?
Particles 1–100 nm in size; high surface area-to-volume ratio.
Uses of nanoparticles.
Sunscreens (UV absorption), catalysts, electronics.
Risks of nanoparticles.
Unknown health/environmental impacts due to small size.
Why are alloys harder than pure metals?
Different-sized atoms disrupt layers, preventing sliding.
Explain conductivity in metals.
Delocalized electrons carry charge.
Why do simple molecules have low boiling points?
Weak intermolecular forces (not bonds) require little energy to overcome.
Compare diamond and graphite.
Diamond: rigid, non-conductive. Graphite: layers, conducts, slippery.
What holds ionic lattices together?
Strong electrostatic forces between + and - ions.
What holds covalent molecules together?
Strong covalent bonds within molecules, weak intermolecular forces between them.
State change: gas → liquid.
Condensation (loss of energy).
Define surface area-to-volume ratio.
As particles shrink, surface area increases relative to volume (key for nanoparticles).
Practical: Why are ionic compounds brittle?
Layers shift, causing like charges to repel and crack.
