Pg 204 #1-6
1. What is an allotrope?
a. Different forms of an element that each have distinctly different physical or chemical properties.
2. Name two elements other than carbon that form allotropes.
a. Oxygen
b. Phosphorus
3. A diamond, a chunk of coal, and your pencil lead contain the same substance:
a. How are their properties different?
i. A diamond has the highest melting point of any element, while graphite is very conductive, so it is used in batteries, and coal is combustible, which is why it is used in grills.
b. Why are their properties different?
i. Their properties are different because of how the atoms of the element are organized in the structure of the substances.
c. What accounts for the differences in the cost of these items?
i. The physical properties, such as luster, appearance, and how common they are in society.
4. How do engineered materials differ from natural materials?
a. Engineered materials differ from natural materials in that they can have properties that are better or worse than the natural material, but they can be made to meet specific needs while natural materials can’t.
5. List two advantages and two disadvantages of using engineered ceramics in high-temperature applications.
a. ADVANTAGES:
i. Increased efficiency of engines
ii. Can operate at higher temperatures than metal engines
b. DISADVANTAGES:
i. They are brittle
ii. Can fracture if exposed to rapid temperature changes.
6. Describe two examples of properties that can be modified in plastics to make them useful for new applications.
a. Softness and pliability, such as in squeeze bottles.
b. They are more useful in wiring to transmit data, such as in phone calls.
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