Topic: Health Risks Visit bookk.msscience.com for Web links to information about health risks due to mercury.
Activity Write a paragraph on how mercury can affect your health.
Dentistry and Dental Materials Dentists have been using amalgam for over 150 years to fill cavities in decayed teeth. Amalgam, a mixture of silver, copper, tin, and mercury, is the familiar “silver filling.” Because amalgam contains mercury, some people are concerned that the use of this type of filling may unnecessarily expose a per- son to mercury vapor. Today dentists have alternatives to amal- gam. New composites, resins, and porcelains are being used to repair decayed, broken, or missing teeth. These new materials are strong, chemically resistant to body fluids, and can be altered to have the natural color of the tooth. Some of the new resins also contain fluoride that will protect the tooth from further decay. Many of these new materials would be useless without the devel- opment of new bonding agents. The new “glues” or bonding agents adhere the new materials to the natural tooth. These bond- ing agents must be strong and chemically resistant to body fluids.
Why are these new dental materials desirable for repairing teeth?
Orthodontists are using new nickel and titanium alloys for the wires on braces. These wires have shape memory. The wires undergo a special heat treatment process to lock in their shapes. If the wires are forced out of their heat-treated shape, the wires will try to return to their original shape. Orthodontists have found these wires useful in straightening crooked teeth. How do you think these wires help to straighten crooked teeth?
Groups 3–12, which are transition elements, are all metals.
Their properties change less than the repre- sentative elements.
The elements in the iron triad are iron, cobalt, and nickel.
Inner Transition Elements
The lanthanide series contains elements from cerium to lutetium.
The lanthanides also are known as the rare earth elements.
The actinide series contains elements from thorium to lawrencium.
State how the elements in the iron triad differ from other transition metals.
Explain the major difference between the lanthanides and actinides.
Explain how mercury is used.
Describe how synthetic elements are made.
Think Critically Iridium and cadmium are both transi- tion elements. Predict which element is toxic and which element is more likely to be a catalyst. Explain.
6. Form Hypotheses How does the appearance of a burned-out lightbulb compare to a new lightbulb? What could explain the difference?
K CHAPTER 4 The Periodic Table