Boron,a metalloid, has a slight luster and conducts electricity at high temperatures like a metal. But like a nonmetal, boron is brittle and does not conduct electricity well at low temperatures.
Carbon is a nonmetal. In graphite,carbon is a soft,brittle solid. It is not reflective,ductile, or malleable.
Figure 3 These elements are examples of metals, nonmetals, and metalloids.
Copper, a metal, is reflective, ductile, malleable, and a good conductor of heat and electricity.
Topic: Elements Visit bookk.msscience.com for Web links to information about how the periodic table was developed.
Activity Select an element and write about how, when, and by whom it was discovered.
Metals If you look at the periodic table, you will notice it is color coded. The colors represent elements that are metals, non- metals, or metalloids. Examples of a metal, a nonmental, and a metalloid are illustrated in Figure 3. With the exception of mer- cury, all the metals are solids, most with high melting points. A metal is an element that has luster, is a good conductor of heat and electricity, is malleable, and is ductile. The ability to reflect light is a property of metals called luster. Many metals can be pressed or pounded into thin sheets or shaped into objects because they are malleable (MAL yuh bul). Metals are also duc- tile (DUK tul), which means that they can be drawn out into wires. Can you think of any items that are made of metals?
Nonmetals and Metalloids Nonmetals are usually gases or brittle solids at room temperature and poor conductors of heat and electricity. There are only 17 nonmetals, but they include many elements that are essential for life—carbon, sulfur, nitro- gen, oxygen, phosphorus, and iodine.
The elements between metals and nonmetals on the periodic table are called metalloids (ME tuh loydz). As you might expect from the name, a metalloid is an element that shares some properties with metals and some with nonmetals. These ele- ments also are called semimetals.
How many elements are nonmetals?
K CHAPTER 4 The Periodic Table