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Chemistry · 2. Bonding and structure

Bonding, structure and material properties

Use microscopic structure to explain melting point, conductivity and solubility.

40 minutesContent version: 2.1
Start the interactive pathwayOpen the virtual experiment

Driving question

Why can substances containing similar elements have very different properties?

Curriculum coverage

Vietnam Chemistry 10; IGCSE atoms, elements and compounds.

Model scope and limitations

Bonding models are representations; electron transfer/sharing is not a full quantum description.

Learning objectives

  • Distinguish ionic, covalent and metallic bonding.
  • Relate simple/giant structures to properties.
  • Explain conductivity using mobile charge carriers.

Prerequisite knowledge

  • Electron structure and ions.

Core knowledge

Ionic structure

Giant ionic lattices have strong attractions; they conduct only when ions can move.

Covalent structure

Simple molecules have relatively weak intermolecular forces; giant covalent structures contain many strong bonds.

Metallic structure

Positive ions with delocalised electrons explain conductivity and malleability.

Worked example

Solid NaCl does not conduct because ions are fixed; molten NaCl conducts because Na⁺ and Cl⁻ can move to electrodes.

Misconceptions to avoid

  • Melting a molecular substance does not break intramolecular covalent bonds; it mainly overcomes intermolecular forces.
  • “Strong” must specify bonds within particles or forces between particles.

Virtual experiment procedure: Metal ions in solution

  1. Observe Cu²⁺ tests with OH⁻ and NH₃.
  2. Describe observations first, then explain using particles/ions.
  3. Compare molecular and net ionic equations.

Safety and cautions

  • Ammonia is irritating and metal salts need proper disposal; simulation does not replace lab protocols.

Evidence to collect

  • A structure–charge carrier–conductivity comparison table.
Open the virtual experiment

Diagnostic check

1. Does solid NaCl conduct electricity?

  1. No
  2. Yes, via free electrons
  3. Only when cold
Show answer and explanation

Correct answer: No

Ions are fixed in lattice positions.

2. What mobile charge carriers exist in a metal?

  1. Delocalised electrons
  2. Free protons
  3. Neutral molecules
Show answer and explanation

Correct answer: Delocalised electrons

Delocalised electrons move through the metallic lattice.

3. Why does diamond have a high melting point?

  1. Giant covalent network
  2. Small molecules
  3. Free ions
Show answer and explanation

Correct answer: Giant covalent network

Much energy is needed to break many covalent bonds.

Application practice

1. When does an ionic substance conduct?

  1. Molten or aqueous with mobile ions
  2. Always as a solid
  3. Only at 0°C
Show answer and explanation

Correct answer: Molten or aqueous with mobile ions

Conduction needs mobile charged particles.

2. Why does graphite conduct but diamond does not?

  1. Graphite has delocalised electrons
  2. Diamond is ionic
  3. Graphite is hotter
Show answer and explanation

Correct answer: Graphite has delocalised electrons

Each C in graphite contributes to a delocalised electron system.

3. When water boils, what is mainly overcome?

  1. Intermolecular forces
  2. All O–H bonds
  3. Nuclear bonds
Show answer and explanation

Correct answer: Intermolecular forces

H₂O molecules remain intact in steam.

Academic references

  1. OpenStax Chemistry 2e — peer-reviewed general chemistry
  2. IUPAC Gold Book — authoritative chemical terminology
  3. BIPM — SI Brochure, 9th edition

This lesson is maintained against the cited sources below. Simulations are learning models and do not replace supervised physical-laboratory safety procedures.

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WebLab STEM
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Đức Tiến — Control & Automation Engineer