The
progression in ideas through the Foundation topics is as follows.
Substances
This section establishes the idea of a substance as being
a special kind of ‘stuff’ with its own identity.
This notion of identity is explored through examining melting
and freezing points, and how we explain these using particle
theory. The particle model animations use different-shaped
particles to represent different substances, and a
notable feature is that the model includes a representation
of the forces between particles. This section then uses
the particle model to help students understand the gas state
and finishes with density.
Mixtures of substances
This section asks students to distinguish between mixtures
of substances and pure samples of a substance. Starter
questions include ‘How do we know if stuff is a mixture?’
and ‘How can we separate mixtures?’ Students
then
compare the melting points of mixtures and pure samples
of substances. There is an explanation of evaporation,
including evaporation at temperatures below boiling point,
in terms of the particle model and energy of particles.
Students also learn about the condensation of atmospheric
water vapour, dissolving, different sorts of mixtures
(e.g. smoke, foam, mist emulsion), solubility, and how mixtures
can be separated.
Changing substances
In this section students learn that substances can change
into other substances, and that chemical change results
in the formation of new substances. The section introduces
the concept of atoms, structures and bonds, and how structure
is related to properties such as melting and boiling point.
Later on in this section, students learn about how to detect
chemical change, as well as different chemical reactions
such as decomposition and reactions in solution.
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