Periodic property metallic character

A FIGURE 9.36 Periodic properties metallic character Metallic character decreases as you move to the right across a period and increases as you move down a column in the periodic table. 

A century ago, Mendeltef used his new periodic table to predict the properties of ekasilicon , later identified as germanium. Some of the predicted properties were metallic character and high m.p. for the element formation of an oxide MOj and of a volatile chloride MCI4. 

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 ... 

Already familiar to the student is the crude but important generalization, Metallic character of the elements in the periodic classification decreases in progressing from left to right in the table but increases in progressing from top to bottom. The term metallic character is a rough and qualitative combination of a number of more specific properties—for example, electrical and thermal conductivity, oxidation potential, basicity of the respective oxide, etc. 

The metallic character of the elements in the periodic table, and the acid-base properties of their oxides, show a distinct trend across periods and down groups. Infer what this trend is. 

The hydrides show the chemical and physical properties one would anticipate from the position of the metal in the periodic table and from the foregoing. The strongly electropositive metals of the first two groups give saline hydrides which physically resemble the corresponding fluorides. The transition metals form metallic or semimetallic hydrides, presumably because of their ability to use d or d-hybrid orbitals which are delocalized into a conduction band. Apart from their metallic character, however, there are no unexpected differences in proper-... 

The members of group of the periodic table show the expected trend in properties with increasing atomic number (f able 21 1) nitrogen is a gas which can be condensed to a liquid only at very low temperatures phosphorus (in the modification called w I tilt phosphorus) is a low-melting non-metal and arsenic, antimony, and bismuth are metalloids with increasing metallic character. 

Perhaps the most interesting thing about the Periodic Table of Elements is how much information is hidden in it. To the untrained eye, the periodic table appears to only show the elemental symbols, elemental names, atomic numbers, and atomic masses. However, someone who knows a bit more chemistry can squeeze much more information out of the same table. You will learn to use the periodic table to check your electron configurations, orbital notations, and Lewis dot notations. You will also learn to use the periodic table to check many relative properties of the elements, such as reactivity, electronegativity, and metallic character. All of this information is there, if you know how to use the table correctly. It is certainly in your best interest to learn as much about the periodic table as possible, because you are allowed to make use of it on many exams and quizzes. If you are able to extract all kinds of information from it, it becomes an incredibly useful cheat sheet, except that you re allowed to use it ... 

In our study of periodicity we learned that metallic character increases toward the left and toward the bottom of the periodic table (Section 4-1) and that oxides of most metals are basic (Section 6-8, part 2). The oxides of some metals (and metalloids) are amphoteric (Section 10-6). In Section 13-17 we described metallic bonding and related the effectiveness of metallic bonding to the characteristic properties of metals. 

Another group trend with />block elements is the increasing tendency towards metallic character in lower periods. As with the chemical trends, the change in structures and properties of the elements appears more of a continuous transition than a sharp borderline (see Topics B2 and D7). The structural distinction between near-neighbor (bonded) atoms and next-near-neighbor (nonbonded) ones... 

This brief examination of oxides of the third-period elements shows that as the metallic character of the elements decreases from left to right across the period, their oxides change from basic to amphoteric to acidic. Metallic oxides are usually basic, and most oxides of nonmetals are acidic. The intermediate properties of the oxides (as... 

Periodic variations in the physical properties of the elements reflect differences in atomic structure. The metaUic character of elements decreases across a period from metals through... 

In general terms, how does each of the following atomic properties influence the metallic character of the main-group elements in a period ... 

The most metallic element is francium at the bottom left of the table. The most nonmetallic element is fluorine. The metallic character of elements within a group increases with period number. This means that within a column, the more metallic elements are at the bottom. The metallic character of elements within a period decreases with group number. This means that within a row, the more metallic elements are on the left. Among the main group atoms, elements diagonal to each other as indicated by the dashed arrows have similar properties because they have a similar metallic character. The noble gases are nonmetals, but they are an exception to the diagonal rule. 

The more an element exhibits the physical and chemical properties of metals, the greater its metallic character. As indicated in Figure 7.12, metallic character generally increases as we proceed down a group of the periodic table and decreases as we proceed right across a period. Let s now examine the close relationships that exist between electron configurations and the properties of metals, nonmetals, and metalloids. 

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