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UNIT 2: STRUCTURE AND PROPERTIES

Unit 2 – Performance Task and Review

 

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Question 35

In steel mills and foundries, a device called an optical or wire pyrometer is often used to measure the approximate temperature of steel that is hot enough to glow by its own emitted light. Research and report on the operating principle of this type of pyrometer and refer to Planck’s theory of light emission in your explanation.

Heat Treatment of Steel
This website discusses pyrometers and the heat-treatment of steel. It describes pyrometers that work in different ways with different mechanisms and with different needs for calibration.

Question 28

In DNA, the pairing of nitrogen bases depends on hydrogen bonding between two molecular structures that must be precisely the right size and shape to bring the hydrogen atoms and lone pair of electrons together. Research and report on the names of the nitrogen bases that bond together in a DNA double helix structure; and on how many hydrogen bonds are formed between the two different base pairings.

Introduction to DNA Structure
This excellent tutorial from the University of Arizona explains the structure of DNA in great detail, but using attractive graphics to demonstrate the various components of the DNA molecule.

Question 40

Describe a carbon nanotube and some of its properties. Hoe does the bonding within the nanotube molecule compare with other forms of pure carbon? What have scientists been able to do with these tubes? List some potential applications of these nanotubes.

A Carbon Nanotube Page
This website provides an overview of the science of nanotubes, followed by several useful lists--of links, books and reviews, references, and commercial suppliers.

All Aboard the Nanotube
This article appears in WordLink, the magazine of the World Economic Forum. The author describes the potential uses of nanotubes, once their technological capabilities have been realized.

 

Question 41

Kevlar is a specialized synthetic material that has some remarkable properties. List some of these properties and describe some different applications. What makes Kevlar so strong? Include some information about molecular structure, shape, and bonding in your answer.

Brains and Kevlar
This corporate website briefly introduces the material, Kevlar, but you'll have to follow links to other parts of Dupont's website to find information about the science and technology of Kevlar.

What Makes Kevlar So Strong?
From the Berkeley Lab, this website explains clearly and succintly, how exactly Kevlar acts as such a strong material. It includes pictures in its description of Kevlar at the atomic level, as well as at the structural level.

 

Question 42

Diamond is the hardest material known and it is used in cutting tools for any other substance, including very hard rocks like granite. And yet, diamonds are cut and polished. How is this possible? Describe the procedure and materials used.

How Diamonds Work
This How Stuff Works webpage explains the origins of diamonds, their properties, and provides links to several other websites that are concerned with diamonds.

Diamonds Shape the World
This American Museum of Natural History website discusses the industrial applications of diamonds, their mining, and the machinery/tools in which they are used.