0.2 Tg physical science - chapter contexts  (Page 2/10)

In the section on pure substances, learners will learn about: elements, the periodic table of elements and compounds as well as to decide what the difference is between a mixture and a compound by using molecular models. The time spent on the guidelines provided for naming compounds and the exercise to consolidate understanding will be worthwhile! You ought to find that the learners will easily understand the text explaining the concepts: metals, semi-metal, non-metals, electrical conductors, semi-conductors and insulators, thermal conductors and insulators as well as magnetic and non-magnetic materials. The text also elaborates on where the specific properties of the listed materials are used in buildings, industrial and home environments as well as in animals and humans. Point out to the learners that as students of the Physical Sciences they need to understand how the physical environment works in order to benefit from it.

The learners need to engage in the three practical investigations listed in this chapter to strengthen their practical ability in a “hands on” way.

Investigate:

• The separation of a salt solution
• Electrical conductivity
• Magnetism

The detailed summary at the end of the chapter and the summary exercise provide a useful self-assessment checklist for the learner and the educator, to make sure that all aspects have been effectively addressed and learnt.

The atom

In this section the idea that matter is made of very small particles (atoms) is developed further and learners are guided in understanding the microscopic nature of matter. Studying the atomic models illustrates that scientific knowledge changes over time as scientists acquire new information.

Studying the atomic models of Thomson, Rutherford and Bohr contribute to form a ‘picture’ of how an atom looks, based on evidence available at that stage. The concepts related to the structure of the atom: protons, neutrons and electrons, isotopes, atomic number and atomic mass are explained in a way that learners will understand. To consolidate learning, learners need to engage in studying the worked examples and do the exercises. By taking part in the suggested Group Discussion activities, learners have the opportunity to develop critical thinking skills and express themselves using the scientific language. The effective use of diagrams clarifies abstract concepts, such as energy quantisation and electron configuration. The text urges learners to understand electron configuration, as valence electrons of the atoms will determine how they react with each other.

The periodic table

The CAPS document requires that learners understand the arrangement of elements in increasing atomic number, and show how periodicity of the physical and chemical properties of the elements relates to electronic structure of the atoms in the periodic table. The content of this section in the learner book will enable learners to understand the underpinning concepts and to develop the skill to use the periodic table to extract data.