Nonmetals characteristic properties

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. 

We learn that the physical and chemical properties of metals are different from those of nonmetals. These properties arise from the fundamental characteristics of atoms, particularly ionization energy. Metalloids display properties that are intermediate between those of metals and those of nonmetals. 

These have the characteristic properties of nonmetals. Like the latter, they vary from being very volatile to very involatile. They are almost always stoicheiometric only in the case of certain polymers does variable composition arise. 

Nonmetallic. Formed generally by the combination of nonmetals and having the characteristic properties of nonmetals. 

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. 

Beryllia ceramics have these characteristics extremely high thermal conductivity, particularly in the lower temperature range excellent dielectric properties outstanding resistance to wetting and corrosion by many metals and nonmetals mechanical properties only slightly less than those of 96% alumina ceramics valuable nuclear properties, including an exceptionally low thermal neutron absorption cross section and ready availability in a wide variety of shapes and sizes. Like alumina and some other ceramics, beryllia is readily metallized by a variety of thick and thin film techniques. 

What are the characteristic properties of metals, nonmetals, and metalloids ... 

The metalloids, also known as semimetals, have the characteristics of both the metals and the nonmetals they conduct electricity and heat better than do the nonmetals, but not as well as the metals do, and they can be shiny or dull their properties are therefore between those of the metals and the nonmetals. 

As elements progress from group 13 to group 17, they show a shift from metallic characteristics to properties of the nonmetals, but the distinctions are not cut-and-dried. Some elements listed in groups 13, 14, 15, and 16 may have both metal-like qualities—metalloids or semiconductors—as well as a few nonmetal properties. 

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. 

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. 

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. 

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. 

The relevance to small particles and indeed massive surfaces now becomes clear, because the preponderance of low CN atoms increases as particle size goes down, and this may turn out to be the most important factor in determining reactivity14 — more important than quantum size effects (i.e. the metal —> nonmetal transition), surface mobility or any of the other properties that are characteristic of very small assemblies of atoms (see Section 3.4). It becomes possible to imagine that activity in catalytic oxidations is solely due... 

Formation of a Galvanic Cell. When a metal or alloy is electrically coupled to another metal or conducting nonmetal in the same electrolyte, a galvanic cell is created. The electromotive force and current of the galvanic cell depend on the properties of the electrolyte and polarization characteristics of anodic and cathodic reactions. The term galvanic corrosion has been employed to identify the corrosion caused by the contact between two metals or conductors with different potentials. It is also called dissimilar metallic corrosion or bimetallic corrosion where metal is the conductor material. 

Recall that the chemical property most characteristic of a metal is the ability to lose its valence electrons. The Group 1A elements are very reactive. They have low ionization energies and react readily with nonmetals to form ionic solids. A typical example involves the reaction of sodium with chlorine to form sodium chloride,... 

Although this theory explains theoretically the experimental observations in the case of ReOj, TiO, and VO, it fails to verify the conductivity characteristics of transition metal oxides such as TiO, VO, MnO, and NiO. Band theory explains the metallic characteristics but fails to account for the electrical properties of insulators or semiconductors and metal-nonmetal transitions because of neglect of electronic correlation inherent in the one-electron approach to the problem. Although there is no universal model for description of the conductivity, magnetic and optical properties of a wide range of materials (e.g., simple and complex oxides, sulfides, phosphides), several models have been proposed (for details, see Refs. 447-453). Of these, a generally accepted one is that described by Goodenough (451). 

The identification of the chemical forms of an element has become an important and challenging research area in environmental and biomedical studies. Two complementary techniques are necessary for trace element speciation. One provides an efficient and reliable separation procedure, and the other provides adequate detection and quantitation [4]. In its various analytical manifestations, chromatography is a powerful tool for the separation of a vast variety of chemical species. Some popular chromatographic detectors, such flame ionization (FID) and thermal conductivity (TCD) detectors are bulk-property detectors, responding to changes produced by eluates in a characteristic mobile-phase physical property [5]. These detectors are effectively universal, but they provide little specific information about the nature of the separated chemical species. Atomic spectroscopy offers the possibility of selectively detecting a wide rang of metals and nonmetals. The use of detectors responsive only to selected elements in a multicomponent mixture drastically reduces the constraints placed on the separation step, as only those components in the mixture which contain the element of interest will be detected... 

Interpreting Data Metalloids combine some of the properties of both metals and nonmetals. Write the word metalloid beneath the Classification heading in the data table for those element samples that display the general characteristics of metalloids. 

The elements have been classified empirically based on similarities in their physical or chemical properties. Metals and nonmetals are distinguished by the presence (or absence) of a characteristic metallic luster, good (or poor) ability to conduct electricity and heat, and malleability (or brittleness). Certain elements (boron, silicon, germanium, arsenic, antimony, and tellurium) resemble metals in some respects and nonmetals in others, and are therefore called semimetals or metalloids. Their ability to conduct electricity, for example, is much worse than metals, but is not essentially zero like the nonmetals. 

Metalloids show some properties that are characteristic of both metals and nonmetals. Many of the metalloids, such as silicon, germanium, and antimony, act as semiconductors, which are important in solid-state electronic circuits. Semiconductors are insulators at lower temperatures, but become conductors at higher temperatures (Section 13-17). The conductivities of metals, by contrast, decrease with increasing temperature. 

The color coding in the periodic table on pages 92 and 93 identifies which elements are metals (blue), nonmetals (yellow), and metalloids (green). The majority of the elements are metals. They occupy the entire left side and center of the periodic table. Nonmetals occupy the upper-right-hand corner. Metalloids are located along the boimdary between metals and non-metals. Each of these classes has characteristic chemical and physical properties, so by knowing whether an element is a metal, nonmetal, or metalloid, you can make predictions about its behavior. Elements are classified as metals, metalloids, or nonmetals on the basis of their physical and chemical properties. 

One way to compare the properties of the representative elements across a period is to examine the properties of a series of similar compounds. Since oxygen combines with almost all elements, we will compare the properties of oxides of the third-period elements to see how metals differ from metalloids and nonmetals. Some elements in the third period (P, S, and Cl) form several types of oxides, but for simplicity we will consider only those oxides in which the elements have the highest oxidation number. Table 8.5 lists a few general characteristics of these oxides. We observed earlier that oxygen... 

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