Metalloids periodic properties

Ion formation is only one pattern of chemical behavior. Many other chemical trends can be traced ultimately to valence electron configurations, but we need the description of chemical bonding that appears in Chapters 9 and 10 to explain such periodic properties. Nevertheless, we can relate important patterns in chemical behavior to the ability of some elements to form ions. One example is the subdivision of the periodic table into metals, nonmetals, and metalloids, first introduced in Chapter 1. 

Some of the metalloids are considered semiconductors. The term metalloids is used in this reference book because these elements do have characteristics of both metals and non-metals, and the term semiconductor refers only to particular elements somewhere between metals and nonmetals. Semiconductors also have properties of both metals and nonmetals. Therefore, they have the ability to act as conductors of electricity and thermal energy (heat), as well as the ability to act as insulators or nonconductors of electricity and heat, depending upon the kind and amount of impurities their crystals contain. Again, following the zigzag steps on the periodic table, the metalloids having properties of both metals and nonmetals are as follows boron, silicon, germanium, arsenic, antimony, tellurium, and polonium. 

The modern periodic table provides us with volumes of information about the elements. Metals are on the left side of the table, nonmetals are on the right side, and metalloids divide these two groups. In general, metals are shiny, malleable, ductile, and conduct electricity. Nonmetals are dull, brittle, and do not conduct electricity (many nonmetals are gases at room temperature). Metalloids have properties of both metals and nonmetals. 

The elements can be divided into three categories—metals, nonmetals, and metalloids. A metal is a good conductor of heat and electricity while a nonmetal is usually a poor conductor of heat and electricity. A metalloid has properties that are intermediate between those of metals and nonmetals. Figure 2.8 shows that the majority of known elements are metals only seventeen elements are nonmetals, and eight elements are metalloids. From left to right across any period, the physical and chemical properties of the elements change gradually from metallic to nonmetallic. 

Metalloids, such as boron (B) and silicon (Si), are the elements that form a diagonal separation zone between metals and nonmetals in the periodic table. Metalloids have properties somewhat between those of metals and nonmetals, and they often exhibit some of the characteristic properties of each type. 

The elements show increasing metallic character down the group (Table 14.6). Carbon has definite nonmetallic properties it forms covalent compounds with nonmetals and ionic compounds with metals. The oxides of carbon and silicon are acidic. Germanium is a typical metalloid in that it exhibits metallic or nonmetallic properties according to the other element present in the compound. Tin and, even more so, lead have definite metallic properties. However, even though tin is classified as a metal, it is not far from the metalloids in the periodic table, and it does have some amphoteric properties. For example, tin reacts with both hot concentrated hydrochloric acid and hot alkali ... 

The elements can be divided into categories metals, nonmetals, and metalloids. Examples of each appear in Figure U. Except for hydrogen, all the elements in the left and central regions of the periodic table are metals. Metals display several characteristic properties. For example, they are good conductors of heat and electricity and usually appear shiny. Metals are malleable, meaning that they can be hammered into thin sheets, and ductile, meaning that they can be drawn into wires. Except for mercury, which is a liquid, all metals are solids at room temperature. 

Diagonal similarities refer to chemical similarities of Period 2 elements of a certain group to Period 3 elements, one group to the right. This effect is particularly evident toward the left side of the periodic table. One example is the pair, B and Si, which are both metalloids with similar properties. Another example is the pair, Li and Mg. They have similar ionic charge densities and electronegativities their compounds are similar in... 

Know the properties of metals, nonmetals, and metalloids and which elements on the periodic table belong to each group. 

There are several general ways to categorize elements in groups 13 to 16. These are metals different in several ways from the transition elements. They range from metallics (other metals) to metalloids (semiconductors) to nonmetals. The elements in these groups are arranged according to their properties, characteristics, and the position of their electrons in their atoms outer shells. These, and other factors, determine how they are depicted in the periodic table. 

Tellurium is a silver-white, brittle crystal with a metallic luster and has semiconductor characteristics. It is a metalloid that shares properties with both metals and nonmetals, and it has some properties similar to selenium and sulfur, located just above it in group 16 of the periodic table. 

Polonium is more metallic in its properties than the elements above it in group 16. It is the only element in group 16 that is naturally radioactive. It is in a position on the periodic table of elements where it can be a metal, metalloid, or nonmetal. It is more often considered a metal because of its electrical conductivity decreases with an increase in temperature. 

Figure 6.6 summarizes different blocks, families, and areas of the periodic table. Most elements can be classified as metals. Metals are solid at room temperature, are good conductors of heat and electricity, and form positive ions. Moving across the table from left to right elements lose their metallic characteristics. The metalloids, also known as the semi-metals, have properties intermediate between metals and nonmetals. Because they display characteristics of both conductors and nonconductors, elements such as silicon and germanium find wide use in the semi-conductor industry. Non-metals are found on the far right of the periodic table. Nonmetals are poor conductors and are gases at room temperature. 

When we classify the elements as metals and nonmetals we see that metals occupy very big part (about 80%) of the periodic table. The elements in B groups (transition elements, actinides and lanthanides) and the elements in the groups, 1 A, 2A and 3A (except hydrogen and boron) are metals. Only the eleven elements H, C, N, O, R S, Se, F, Cl, Br and I are nonmetals and the elements in group 8A are noble gases. However, among these elements, B, Si, Ge, As, Sb, Te, Po and At are metalloids and Sn, Pb and Bi and Be have metallic properties. 

Metals are located on the left side of the periodic table. Metals tend to form cations, are generally ductile and malleable, and are good electrical and thermal conductors. Nonmetals are located on the right side of the periodic table. Nonmetals tend to form anions and have a wide variety of physical properties. Metalloids look like metals but have electrical conductivity intermediate between metals and nonmetals. For this reason, metalloids are called semiconductors. 

From the electronegativities shown in Figs. 2.4.2 and 2.4.3, it is seen that metals are less electronegative, with xs < 2, nonmetals are more electronegative, with xs > 2. Around xs 2, we have metalloid elements such as B, Si Ge, Sb, and Bi. Most of these elements have semi-conducting properties. For elements of the same group, xs decreases as we go down the Periodic Table. However, because of relativistic effects, for transition metals from group 7 to... 

You have seen how the periodic table organizes elements so that those with similar properties are in the same group. You have also seen how the periodic table distinguishes among metals, non-metals, and metalloids. Other details of the organization of the periodic table may seem baffling, however. Why, for example, are there different numbers of elements in the periods ... 

In other words, state what you think happens to the acid-base properties of oxides as you go across a period and down a group. Make a quick sketch of the periodic table to illustrate this trend. Flow would you describe the acid-base properties of the metalloids (Use your knowledge of the physical properties of the metalloids to help you make your inference.)... 

The semimetals, or metalloids, are known to exhibit some of the properties of metals and some of those of nonmetals. The semimetals are B, Si, Ge, As, Sb, Te, and At. They are highlighted in bold in the partial periodic table in Figure 4.1. The elements located to the left of the semimetals are the metals those to the right of the semimetals are the nonmetals. Identifying an element as a metal, nonmetal, or semimetal is important in identifying periodic trends and in identifying the types of bonds that atoms will form with each other. 

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