transition elements for BSc and MSc students
- 1. The Transition Metals, the Lanthanides and the Antinides
- 2. The Metals in the Middle • Groups 3-12 are called the transition elements. • All of them are metals. Transition Elements 3 • Across any period from Group 3 through 12, the properties of the elements change less noticeably than they do across a period of representative elements. • Most transition elements are found combined with other elements in ores.
- 3. The Iron Triad Transition Elements 3 • These elements, among others, have magnetic properties. • Three elements in period 4—iron, cobalt, and nickel—have such similar properties that they are known as the iron triad.
- 4. The Iron Triad • Industrial magnets are made from an alloy of nickel, cobalt, and aluminum. Transition Elements 3 • Nickel is used in batteries along with cadmium. • Iron is a necessary part of hemoglobin, the substance that transports oxygen in the blood. • Iron also is mixed with other metals and with carbon to create a variety of steels with different properties.
- 5. Uses of Transition Elements • Most transition metals have higher melting points than the representative elements. Transition Elements 3 • The filaments of lightbulbs are made of tungsten, element 74.
- 6. Uses of Transition Elements Transition Elements 3 • Tungsten has the highest melting point of any metal (3,410°C) and will not melt when a current passes through it.
- 7. Uses of Transition Elements • Mercury, which has the lowest melting point of any metal (–39°C), is used in thermometers and in barometers. Transition Elements 3 • Mercury is the only metal that is a liquid at room temperatures. • Like many of the heavy metals, mercury is poisonous to living beings.
- 8. Uses of Transition Elements • Chromium’s name comes from the Greek word for color, chrome. Transition Elements 3 • Many other transition elements combine to form substances with brilliant colors.
- 9. Uses of Transition Elements • Ruthenium, rhodium, palladium, osmium, iridium, and platinum are sometimes called the platinum group because they have similar properties. Transition Elements 3 • They do not combine as easily with other elements. • As a result, they can be used as catalysts.
- 10. Uses of Transition Elements • A catalyst is a substance that can make something happen faster but is not changed itself. Transition Elements 3 • Other transition elements, such as nickel, zinc, and cobalt, can be used as catalysts.
- 11. Inner Transition Elements • There are two series of inner transition elements. Transition Elements 3 • The first series, from cerium to lutetium, is called the lanthanides. • The second series of elements, from thorium to lawrencium, is called the actinides.
- 12. The Lanthanides • The lanthanides are soft metals that can be cut with a knife. Transition Elements 3 • The elements are so similar that they are hard to separate when they occur in the same ore, which they often do. • Despite the name rare earth, the lanthanides are not as rare as originally thought. • Cerium makes up 50 percent of an alloy called misch (MIHSH) metal. • Flints in lighters are made from misch metal.
- 13. The Actinides • All the actinides are radioactive. Transition Elements 3 • The nuclei of atoms of radioactive elements are unstable and decay to form other elements. • Thorium, protactinium, and uranium are the only actinides that now are found naturally on Earth. • Uranium is found in Earth’s crust because its half-life is long—4.5 billion years.
- 14. The Actinides • All other actinides are synthetic elements. Transition Elements 3 • Synthetic elements are made in laboratories and nuclear reactors. • Plutonium is used as a fuel in nuclear power plants. • Americium is used in some home smoke detectors. • Californium-252 is used to kill cancer cells.
- 15. Dentistry and Dental Materials • Dentists have been using amalgam for over 150 years to fill cavities in decayed teeth. Transition Elements 3 • Amalgam, a mixture of silver, copper, tin, and mercury, is the familiar “silver filling.”
- 16. Dentistry and Dental Materials • Because amalgam contains mercury, some people are concerned that the use of this particular type of filling may unnecessarily expose a person to mercury vapor. Transition Elements 3
- 17. Dentistry and Dental Materials Transition Elements 3 • Today dentists have alternatives to amalgam. New composites, resins, and porcelains are being used to repair decayed, broken, or missing teeth.
- 18. Section Check 3 Which three elements are known as “the iron triad”? Question 1 The iron triad consists of iron, cobalt, and nickel. They are called this because of their similar properties. Answer
- 19. Section Check 3 Which group consists of ruthenium, rhodium, palladium, osmium, iridium, and platinum? Question 2 The answer is the platinum group. These elements all have similar properties, which is why they are grouped together. Answer
- 20. Section Check 3 What is most notable about the nuclei of the actinides? Question 3 The nuclei of actinides are unstable. All the actinides are radioactive, which means they decay to form other elements. Answer
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