Nonmetals

Fundamentals of Chemistry DOE-HDBK-1015/1-93 THE PERIODIC TABLE Rev. 0 CH-01 Page 17 Most people are familiar with metals' physical properties. They are usually hard and strong, capable of being shaped mechanically (malleable and ductile), and good conductors of heat and electricity, and they have lustrous surfaces when clean. More important for chemical classification are the chemical properties of metals because the physical properties are not common to all metals. For example, mercury (Hg) is a metal, although it is a liquid at room temperature, and sodium is a metal although it is not at all hard or strong. Metals can be involved in a wide range of chemical reactions. Their reactions with water range from violent with sodium and potassium to imperceptible with gold and platinum. Metals are divided into the following two categories. 1. The light metals, which are soft, have a low density, are very reactive chemically, and are unsatisfactory as structural materials. 2. The transition metals, which are hard, have a high density, do not react readily, and are useful structural materials. The metals in Category 1 are located at the far left of the table (Groups IA and IIA). The metals in Category 2 are located in the middle of the table (the B groups). Nonmetals The nonmetals occupy the part of the periodic table to the right of the heavy, step-like line. (refer to Figure 3 and Figure 4) In general, the physical properties of the nonmetals are the opposite of those attributed to metals. Nonmetals are often gases at room temperature. The nonmetals that are solids are not lustrous, are not malleable or ductile, and are poor conductors of heat and electricity. Some nonmetals are very reactive, but the nature of the reactions is different from that of metals. Nonmetals tend to gain electrons to form negative ions rather than to lose electrons to form positive ions. The six elements in Group 0 represent a special subclass of nonmetals. They are all very unreactive gases, so they are called the inert gases. For many years it was believed that the inert gases would not and could not participate in chemical reactions. In 1962, the first true compounds of an inert gas, XeF and XePtF , were positively 4 6 identified. Since that time, several other compounds have been prepared. The preparation of these compounds requires special conditions; under ordinary conditions, the inert gases may be considered nonreactive. Semi-Metals