Understandings:
- Atoms of different elements combine in fixed ratios to form compounds, which have different properties from their component elements.
- Mixtures contain more than one element and/or compound that are not chemically bonded together and so retain their individual properties.
- Mixtures are either homogeneous or heterogeneous.
Applications and skills:
- Deduction of chemical equations when reactants and products are specified.
- Application of the state symbols (s), (l), (g) and (aq) in equations.
- Explanation of observable changes in physical properties and temperature during changes of state
. Guidance:
- Balancing of equations should include a variety of types of reactions.
- Names of the changes of state—melting, freezing, vaporization (evaporation and boiling), condensation, sublimation and deposition—should be covered.
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International-mindedness:
- Chemical symbols and equations are international, enabling effective communication amongst scientists without need for translation.
- IUPAC (International Union of Pure and Applied Chemistry) is the world authority in developing standardized nomenclature for both organic and inorganic compounds.
Theory of knowledge:
- Chemical equations are the “language” of chemistry. How does the use of universal languages help and hinder the pursuit of knowledge?
- The discovery of oxygen, which overturned the phlogiston theory of combustion, is an example of a paradigm shift. How does scientific knowledge progress?
Utilization:
- Refrigeration and how it is related to the changes of state.
- Atom economy.
- Freeze-drying of foods
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