AS 91164 Structure and bonding:Practice question 1

The structurfe of quartz

Silicon and oxygen atoms are arranged in a three dimensional covalent network. A portion of such a framework is shown here. In this arrangement, the stoichiometry is reduced to SiO2, (each silicon has a half share of four oxygens) which is often called silica. A collection of small pieces of quartz is sand.

Tackle both questions on quartz and zinc below.

Oscars: Structure and bonding videos

Students have done their own research into why ionic solids will conduct electricity in aqueous solution or in the molten state. These videos illustrate their initial learning and show areas where more work needs to be done. See the key points after the video clips




Ionic compounds.

  • Bonds which hold ionic compounds together are the strong electrostatic forces attractions beween positive and negative ions.

  • Ions are held tightly in a lattice and are not free to move. Ionic solids do not conduct electricity.

  • Ionic solids are hard and brittle with high melting and boiling points

  • Ionic solids often dissolve in polar solvents. They dissolve in water when the polar molecules attract the postive and negative ions free from the lattice.

  • When ionic compounds are dissolved in water or in the molten state the ions are free to move under the influence of an electric field.

  • When aqueous solutions of ionic compounds conduct electricity it is the ions that carry the charge.

  • When molten ionic compounds conduct electricity it is the ions that carry the charge.

NCEA Level 2 Chemistry: Structure and Bonding “The Oscars”

Last year’s structure and bonding ‘Oscars” competition produced some excellent results. The task is similar again this year.

You have to prepare a brief video that will explain to your peers why it is that ionic compounds will conduct electricity when they are either in a molten state or in aqueous solution. Your video could be a demonstration/presentation or perhaps you can think of other ways that the concepts involved could be explained.

Equipment available:

  1. power supply
  2. beakers
  3. ionic compounds such as salt, copper chloride
  4. light bulbs

The videos will be judged on the following points.

  • Ionic compounds have the ability to conduct electricity in the molten state. This must be clearly illustrated and explained
  •  Ionic compounds can conduct electricity in  aqueous solution. Again a clear illustration and explanation is necessary
  • other points to cover include the solubility of ionic compounds in aqueous solution and any chemical reactions that occur when electrolysis is taking place. Electrodes.

You can work in Groups, a maximum of four.

Finally the group with the best video presentation get to keep “”Oscar” this year. This is an opportunity to produce a learning experience that is both informative and entertaining.

The challenge: Last years sixth form were a truly talented bunch of students, can you improve on their performance?

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