Ex. 4. Give detailed answers to the following questions:
1. In what form docs silicon occur in nature? 2. What is the structure
of quartz; what arc the properties of this mineral? 3. What is the structure
of silicic acid; what arc the properties of this acid? 4. In what living
processes in animals or men docs silicon take part?
Ex. 5. Discuss the following topics:
1. An Abundance of Silicon.
2. The Structure of Si02 Molecule.
3. Properties and Structure of Quartz, Cristobalitc and Tridymitc.
4. The Role of Silicon in Living Processes.
DO YOU KNOW THAT...
Although the compounds of silicon have been used for many centuries,
the element was prepared only at the beginning of the 19th ccntuiy. At
present, there arc several methods of obtaining silicon. One of them is to
heat silicon dioxide with magnesium:
SiO: + 2Mg = Si + 2MgO.
One way of preparing silicon commercially is by reducing SiOj with
carbon in an electric fumacc.
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