Starter quiz
- What type of bond typically forms between two non-metal atoms?
- Ionic bond
- Covalent bond ✓
- Metallic bond
-
How many pairs of electrons are shared between two carbon atoms in ethene (shown in the diagram)?- 1
- 2 ✓
- 3
- 4
- 8
-
- Which of the following is an example of a molecule formed by covalent bonding?
- NaCl
- MgO
- CO₂ ✓
- Fe
-
- How many electrons are shared in a single covalent bond?
- '2' ✓
- A displayed formula represents a covalent substance, showing ______ to represent shared pairs of electrons between atoms.
- 'lines' ✓
- Arrange the following molecules by the number of covalent bonds each has, from least to most:
- 1⇔H₂
- 2⇔O₂
- 3⇔N₂
- 4⇔CH₄
Exit quiz
- What is the typical size of atomic radii and bond lengths?
- 10⁻⁶ m
- 10⁻⁸ m
- 10⁻¹⁰ m ✓
- 10⁻¹ ²m
-
- Why can't simple covalent substances conduct electricity?
- They have no atoms.
- They have no free moving electrons. ✓
- They have no electrons.
- They are too small.
- They have no free moving ions. ✓
-
- Giant covalent structures have high melting and boiling points because strong ______ need to be broken, which requires a lot of energy.
- 'covalent bonds' ✓
- What are intermolecular forces?
- Strong forces between atoms.
- Forces of attraction between molecules. ✓
- Forces that hold nuclei together.
- Forces that repel electrons.
-
- Which of the following are true of polymers?
- Most polymers exist in the arrangement of the solid state at room temperature. ✓
- Some polymers are made up of smaller molecules called monomers.
- They have a simple covalent structure (molecules). ✓
- They conduct electricity well.
- They are held together by covalent bonds. ✓
-
- What happens during a change of state in simple covalent substances?
- Covalent bonds are broken.
- Intermolecular forces are overcome. ✓
- Atoms are rearranged.
- Molecules move farther apart. ✓
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Worksheet
Presentation
Video
Lesson Details
Key learning points
- 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.
Common misconception
Pupils often think that covalent bonds are broken when any covalent structure undergoes a change of state; not just those in giant covalent structures.
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.
Keywords
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