Metalloid elements

Germanium [7440-56-4] Ge, at. no. 32, having electronic configuration [Ar] is a semiconducting metalloid element found in Group 14 (IVA),... 

Metallic Glasses. Under highly speciali2ed conditions, the crystalline stmcture of some metals and alloys can be suppressed and they form glasses. These amorphous metals can be made from transition-metal alloys, eg, nickel—2irconium, or transition or noble metals ia combination with metalloid elements, eg, alloys of palladium and siUcon or alloys of iron, phosphoms, and carbon. 

Germanium was the semiconductor material used in the development of the transistor in the early 1950s. However, it exhibits high junction leakage current due to its narrow bandgap and is now largely replaced by silicon. It is a brittle metalloid element with semiconductor characteristics. The properties of germanium are summarized in Table 8.3.1 lP l... 

Regardless of their possible metallic properties, metal-rich Zintl system or phases are defined here as cation-rich compounds exhibiting anionic moieties of metal or metalloid elements whose structures can be generally understood by applying the classical or modern electron counting rules for molecules. 

These studies show that radon can be classified as a metalloid element, together with boron, silicon, germanium, arsenic, antimony, tellurium, polonium, and astatine. Like these elements, radon lies on the diagonal of the Periodic Table between the true metals and nonmetals (Figure 5) and exhibits some of the characteristics of both (Stein, 1985). 

Figure 5. The arrangement of the metalloid elements (dark shading) in the Periodic Table.

Stein, L., New Evidence that Radon Is a Metalloid Element Ion-Exchange Reactions of Cationic Radon, J. Chem. Soc., Chem. Comm. 1631-1632 (1985). 

You should highlight or color the metalloid elements on the periodic table for practice to help you locate the metals and nonmetals. Left = Metals Right = Nonmetals. 

Some authorities begin and end the transition elements at different groups in the periodic table. The transition elements sometimes continue beyond group 12 to include some metallic and semiconducting (metalloids) elements in groups 14, 15, and 16. These elements are presented in different sections. 

Symbol Sb atomic number 51 atomic weight 121.75 Group VA (group 15) element atomic radius 1.41A ionic radius 86 + 0.76A covalent radius 1.21A electronic configuration [Kr] 4di°5s25p3 a metalloid element electronegativity 1.82 (Allred-Rochow type) valence states +5, +3, 0 and -3 isotopes and natural abundance Sb-121 (57.3%), Sb-123 (42.7%)... 

Symbol As atomic number 33 atomic weight 74.922 covalent radius AsS+ 1.2 lA electron configuration [Ar] 4s23di°4p3 a Group VA (Group 15) metalloid element electronegativity 2.20 (Allred-Rochow type) principal valence states, -1-5, +3, 0, and -3 stable isotope As-75. 

Symbol B atomic number 5 atomic weight 10.811 a Group III A (Group 13) metalloid element atomic volume 4.70 cc/g-atom electron affinity 0.277 eV electronic configuration Is22s22pi valence state +3 naturally occurring stable isotopes are B-10 and B-11 and their abundance 19.57% and 80.43%, respectively. 

Anhydrous cobalt(III) fluoride reacts with many nonmetallic and metalloid elements including bromine, iodine, sulfur, phosphorus, carbon, arsenic, and sihcon. It fluorinates these elements, and is reduced to Co2+. 

Fluorine also reacts with other halogens, forming interhalogen compounds. While with bromine and iodine it reacts vigorously at ordinary temperatures, with chlorine the reaction occurs at 200°C. Such interhalogen products with these halogens include iodine heptafluoride, bromine trifluoride, bromine pentafluoride, and chlorine trifluoride. Metalloid elements, such as arsenic, silicon, selenium, and boron also inflame in a stream of fluorine, forming fluorides. 

The metal combines with sulfur and phosphorous on heating, forming the sulfide and phosphide salts, respectively. Metalloid elements, such as arsenic, antimony, selenium and tellurium also combine with indium at elevated temperatures, forming their respective binary salts. 

Lanthanum combines with nitrogen, carbon, sulfur and phosphorus at elevated temperatures, forming binary salts. Also, with metalloid elements such as boron, silicon, selenium, and arsenic, similar reactions occur at high temperatures forming similar binary compounds. 

Water reacts with nonmetals and metalloid elements at very high temperatures forming oxides ... 

The metal reacts with halogens above 200°C forming its trihalides. It combines with nitrogen above 1,000°C producing a nitride, YN. It combines at elevated temperatures forming binary compounds with most nonmetals and some metalloid elements such as hydrogen, sulfur, carbon, phosphorus, silicon, and selenium. 

In Fig. 5 a minimum as in the metals is observed in the curves of the compounds with more metalloidic elements. For AnAs and AnSh this minimum tends to disappear. After the minimum (see AnN), there is a decreasing trend, which can be explained in terms of actinide contraction. Between PuN and AmN, a jump is seen, which is similar to the one met in metals (see Fig. 2). 

Metallic Solid type of solid characterized by delocalized electrons and metal atoms occupying lattice points Metalloid elements have properties intermediate between metals and nonmetals Mixture combination of two or more substances where the individual substances maintain their identity Moderator a material such as graphite or deuterium used to slow down neutrons in nuclear reactors... 

An interstitial compound consists of a metal or metals and certain metalloid elements, in which the metalloid atoms occupy the interstices between the atoms of the metal lattice. Compounds of this type are, for example. TaC, TiC, ZrC. NbC, and similar compounds of carbon, nitrogen, boron, and hydrogen with metals. 

The chemistry of a class of organometallic compounds that contain a linkage between two different metallic and/or metalloidal elements has recently been the subject of considerable study (195, 207), but only very little interest has been shown in such compounds with the silicon-silicon-metal bond. Only a few derivatives of mercury and alkali metals are known. 

In contrast, use of metalloid elements, such as silicon, tin antimony or boron, which can form weak covalent bonds with oxygen, nitrogen or sulfur substituents during the course of the reaction, results in templated products that may be obtained metal-free by simple hydrolysis. These covalent template reactions (the M—X bond is essentially covalent in these cases) also have the advantage that the... 

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... 

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