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Year 10 - Science

Properties of covalent substances

Structure and bonding

Unit Summary

This unit explores changes of state, particle kinetics, and energy transfers in relation to chemical bonding, including ionic, covalent, and metallic bonds. It examines carbon's unique bonding properties, leading to organic compounds and materials like diamond, graphite, fullerenes, and graphene.

Lesson Summary

You will learn to describe some different structures that non-metal atoms can form using covalent bonding and describe the properties of covalent compounds.

Key Notes

  • Typical atomic radii, and bond length, are in the order of 10⁻¹⁰m.
  • Non-metal elements and non-metal compounds form covalent structures.
  • Simple covalent substances have no free moving charge carriers so cannot conduct electricity (some giant covalent can).
  • Small molecules are usually gases or liquids with relatively low melting and boiling points.
  • Giant covalent structures have high melting/boiling points because strong covalent bonds need to be broken.

Vocabulary To Learn

  • molecule: a particle consisting of a fixed number of (two or more) non-metal atoms covalently bonded together
  • covalent bond: the strong electrostatic force of attraction between a shared pair of electrons and the nuclei of bonded atoms
  • intermolecular forces: the weak forces of attraction between molecules and molecular substances
  • giant covalent structure: a substance that has a large regular arrangement of atoms all joined together by covalent bonds
  • polymer: a long chain molecule formed by joining small molecules (monomers) together by covalent bonds

Common Mistakes To Avoid

  • Pupils often think that covalent bonds are broken when any covalent structure undergoes a change of state; not just those in giant covalent structures.

3 Quick Questions (With Answers)

1. Explain the scientific idea in this lesson using two key points.

Typical atomic radii, and bond length, are in the order of 10⁻¹⁰m. Non-metal elements and non-metal compounds form covalent structures.

2. Define this scientific word and use it in context. 'molecule'

a particle consisting of a fixed number of (two or more) non-metal atoms covalently bonded together. Include the word in a full scientific explanation, not as a single label.

3. Correct this common scientific misunderstanding.

Mistake: Pupils often think that covalent bonds are broken when any covalent structure undergoes a change of state; not just those in giant covalent structures. Correction: Use physical models to show the difference between a simple covalent structure and a giant covalent structure. Explain that it is the weak intermolecular forces that are overcome when a simple covalent molecule changes state.

More Lessons In This Unit

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