Background
Water, one of the simplest substances on Earth, exhibits interesting properties that are not predicted by looking at the trends of the periodic table. However, chemical bonding – a foundational concept in chemistry – and the intermolecular forces that occur between water molecules can explain these anomalous properties. In fact, the properties of all materials can be explained by the way their atoms are bonded together, as well as the intermolecular forces that exist between molecules. Student understanding of these submicroscopic concepts can be enhanced by constructing compounds using molecular models, demonstrating how different types of bonds and intermolecular forces contribute to the behaviour of materials.
As the population of Earth and the demand for resources increases, chemists are increasingly expected to use their knowledge of materials to ensure a safer and greener future for our planet. Therefore, the 12 principles of green chemistry were developed as a framework to design more sustainable chemicals, processes, and products.
In the first part of this program, students examine the bonding in water and examine the concepts of polarity and hydrogen bonding. They create ionic lattices and investigate how many ionic substances can dissolve in water. They use these concepts to make predictions and explain everyday phenomena. In the final session students will create a sustainable solvent using a renewable feedstock to demonstrate how chemistry will contribute to the transition from a liner to a circular economy.
Prior Knowledge
Students should have covered Atomic structure and electronic configuration.
Learning Intentions
In this program students will:
- Consolidate their understanding of ionic and covalent bonding through the use molecular models.
- Extend their understanding of the properties of ionic and covalent compounds and the concepts of polarity and hydrogen bonding through observation and analysis of simple experiments.
- Be introduced to green chemistry and develop their lab skills by extracting a sustainable solvent from a renewable feedstock.
Activities
Students will:
- Construct covalent compounds and ionic lattices and demonstrate the dissolution of polar compounds in water using molecular models.
- Conduct simple experiments to investigate the properties of water and ionic compounds.
- Observe what happens to polar and non-polar molecules in different solvents.
- Extract limonene from citrus fruits to demonstrate a solvent that can be made from renewable feedstocks as part of a circular economy.
Note:
- Maximum of 1 class per day.
VCE links
Area of Study 1: How do the chemical structures of materials explain their properties and reactions?
Covalent substances
- Polar and non-polar character with reference to the shape of the molecule
- The relative strengths of intramolecular bonding (covalent bonding) and intermolecular forces (dispersion forces, dipole-dipole attraction and hydrogen bonding)
- Physical properties of molecular substances (including melting points and boiling points and non-conduction of electricity) with reference to their structure
Ionic compounds
- The common properties of ionic compounds (brittleness, hardness, melting point, difference in electrical conductivity in solid and molten liquid states), with reference to the nature of ionic bonding and crystal structure
Separation and identification of the components of mixtures
- Polar and non-polar character with reference to the solubility of polar solutes dissolving in polar solvents and non-polar solutes dissolving in non-polar solvents
Area of Study 3: How can chemical principles be applied to create a more sustainable future?
Sustainability
- Sustainability concepts and principles: green chemistry principles, sustainable development, and the transition from a linear economy towards a circular economy
