Chemical elements metalloids

Krebs, Robert E. The history and use of our earth s chemical elements a reference guide. Westport (CT) Greenwood P, 1998. ix, 346p. ISBN 0-313-30123-9 A short history of chemistry — Atomic structure The periodic table of the chemical elements — Alkali metals and alkali earth metals - Transition elements metals to nonmetals — Metallics and metalloids - Metalloids and nonmetals — Halogens and noble gases - Lanthanide series (rare-earth elements) — Actinide, transuranic, and transactinide series... 

The 92 chemical elements that occur naturally in the earth can be divided into two main groups metals and nonmetals. Although the distinction between the two is not always sharp and clear, it can be said that over 70 of the 92 elements are metals among the fewer than 22 remaining non-metals, six are known as metalloids, which have properties that fall between those of metals and nonmetals (see Appendix I). 

One path of research resulting from the discovery of ferrocene has been concerned with the synthesis and structural elucidation of cyclopentadienyl derivatives of other metals and metalloids. At the present time, over 60 chemical elements have been found to form one or more cyclopentadienyl compounds. This topic has recently been reviewed by the present author as well as by others (17, 83, 125). 

METALLOID. A chemical element lhai may exhibit physical and chemical properties both of a melal anti a noimielal sumeliines is referred in as a meiallnid. Antimony, arsenic, and tellurium are examples, l ess frequently, metalloid refers to elements, such as carbon, silicon, phosphorus, and sulfur, which are added in small amounts in tlie manufacture of iron and steel. 

Metalloid (semi-metal) Any of the class of chemical elements intermediate in properties between metals and non-metals, for example boron and silicon. 

Metallurgically influenced corrosion is mainly composed of the corrosion due to chemical composition (alloying elements, metalloids and impurities), metallurgical properties (metallic phases, grain joints) and fabrication procedures (thermal treatments, lamination and welding). Figure 6.24 shows weld zone, dealloying, exfoliation and internal modes of attack. 

Metalloid. An element of metallic appearance but poor electric conductivity, such as boron or silicon or germanium. Chemically, the metalloids are not so strongly electropositive as the metals and tend principally toward covalent bonding. 

Germanium is a metalloid. A metalloid is an element that has characteristics of both metals and non-metals. Germanium is located in the middle of the carbon family, which is Group 14 (IVA) in the periodic table. The periodic table is a chart that shows how chemical elements are related to each other. Carbon and silicon are above germanium and tin and lead are below it. 

Semi-metals or metalloids are a very small group of elements found in the periodic table of elements along the zig-zag line that distinguishes metals from non-metals and is drawn from between boron and aluminum to the border between polonium and astatine. Elements to the upper right of this line are nonmetals while metals are to the lower left. Together with metals and nonmetals, metalloids form one of the three categories of chemical elements as classified by ionization and bonding properties [1, 2]. 

The heavy metal in the environment collocation refers to any metallic chemical element and some metalloids (e.g. arsenic) that are toxic or poisonous for living organisms even at low concentration, e.g. Pb, Cd, Hg, As, H, Cr. They originate in the Earth s crust as well as in the majority of wastes resulting from anthropogenic activities. Toxic effects of other heavy metals (Cr, Mo, Ni, As, Se etc.) have to be considered separately from the effects of biologic doses in which they exert their vital role. 

The names of a few chemical elements are very similar to the names of planets in the solar system. List these elements, along with their chemical symbols and atomic numbers. Tell whether each element is a metal, nonmetal, or metalloid. 

While scientists categorize the chemical elements as metals, non-metals, and metalloids largely based on the elements abilities to conduct electricity at normal temperatures and pressures, there are other distinctions taken into account when classifying the elements in the periodic table. The alkali metals, for example, are metals, but have such special properties that they are given their own classification. The same is true for the alkaline earths. Both families of elements appear in the two columns on the far left side of the periodic table. (See the following table, which shows the relative positions of the alkali metals and alkaline earths compared with the metals in columns IIIB, IVB, and VB in the periodic table on page 124.)... 

As is one of the few chemical elements which is universally associated with the word poison . This reputation is not undeserved, for over the centuries, many deaths can be attributed to the administration of arsenic trioxide as inheritance powder . The metalloid has a dual reputation, for its use in medicine in earlier times is equally well documented. As was widely prescribed to treat skin diseases, fevers, malarial disorders, syphilis, lumbago, epilepsy, anemia, ulcers, etc ... 

FIGURE B.12 The location ot the seven elements commonly regarded as metalloids these elements have characteristics of both metals and nonmetals. Other elements, notably beryllium and bismuth, are sometimes included in the classification. Boron (B), although not resembling a metal in appearance, is included because it resembles silicon (Si) chemically. 

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. 

Until quite recently, chemical interest in the metalloids consisted mainly of isolated curiosities, such as the poisonous nature of arsenic and the mildly therapeutic value of borax. The development of metalloid semiconductors, which we describe in Chapter 10, focused intense study on these elements. 

Violante A, Krishnamurti GSR, Pigna M (2008) Mobility of trace elements in soil environments. In Violante A, Huang PM and Gadd G (eds) Wiley-JUPAC series on biophysico-chemical processes of metals and metalloids in soil environments. John Wiley Sons, Hoboken, USA Waltham AC, Eick MJ (2002) Kinetic of arsenic adsorption on goethite in the presence of sorbed silicic acid. Soil Sci Soc Am J 66 818-825 Waychunas GA, Fuller CC, Rea BA, Davis J (1996) Wide angle X-ray scattering (WAXS) study of two-line ferrihydrite structure Effect of arsenate sorption and counterion variation and comparison with EXAFS results. Geochim Cos-mochim Acta 60 1765-1781... 

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