Using the Periodic Table to Understand Trends in Properties
From the last section, you may have noticed some trends in the reactivity of elements as you move from left to right on the periodic table. The most reactive metals are on the left side of the periodic table, and the most reactive nonmetals, except for elements of group 18, are on the right side. From left to right, the metals change from having a strong metallic character to having a weak metallic character. Metallic character includes all of the physical and chemical properties used to identify metals.
The nonmetals closest to the central region of the table have the weakest nonmetallic character. Nonmetallic character includes all of the physical and chemical properties used to identify nonmetals. As you continue to the right, the nonmetals have stronger and stronger nonmetallic character. Being chemically unreactive, the noble gases are excluded from this trend. Note that these are general trends in metallic and nonmetallic characters, but there are exceptions. For example, as we move across the transition metals, the trend in reactivity of metals is less pronounced. Transition metals do not follow a general trend and exhibit a variation in reactivity.
Understanding the trends in properties across a period and understanding that the number of valence electrons is the basis for these trends can help you predict properties of elements. For example, to compare elements, you need to locate their relative position first, then, based on the trends you just learned, you can compare their reactivity and metallic or nonmetallic character.
Scientists make use of the information provided by the periodic table to decide which elements to incorporate into new technologies. Knowing how elements behave and what to expect about their behavior under various conditions makes it possible to focus on workable engineering solutions without wasting time testing each and every element for an application. For example, bioengineering researchers were quickly able to choose titanium as a metal to use in constructing artificial joints for use in humans. Titanium is a transition metal that is light and very strong, yet very unreactive. These properties make it a good material for long-term use when surgically implanted into living tissue.
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