Metalloids Elements with properties

Metalloids Elements with properties intermediate between metals and nonmetals B, Si, Ge, As, Sb, Te, Po, and At. 

Metalloids Elements with properties Intermediate between those of metals and nonmetals. and falling between them In the periodic table Semiconductors Metalloid elements with electrical conductivity Intermediate between that of metals and nonmetals... 

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... 

Lead is a bluish-white, heavy metallic element with properties that are more metal-like than the properties of metalloids or nonmetals. Lead can be found in its native state, meaning that elemental metallic lead can be found in deposits in the Earth s crust. However, most lead is first mined as galena ore (lead sulfide, PbS). The galena is mixed with lead sulfate, lead sulfide,... 

Metalloids An element with properties similar to both metals and nonmetals. 

A metalloid or semimetal is an element with properties that are intermediate between those of metals and nonmetals, such as semiconductivity. They are found between metals and nonmetals in the periodic table (see shaded elements in Figure 1.2). 

Metalloid (or semimetal) An element with properties that are intermediate between those of metals and nonmetals such as semiconductivity. 

Silicon is a metalloid, an element with properties of both metals and non-metals. Silicon exists in two allotropic forms. Allotropes are forms of an element with different physical and chemical properties. One allotrope is in the form of shiny, grayish-black, needle-like crystals, or flat plates. The second allotrope has no crystal structure and usually occurs as a brown powder. 

Metalloids are elements with properties intermediate between those of metals and nonmetals. Because the definition of metallic character depends on a combination of properties, there may be some variation in the elements identified as metalloids in different sources. Astatine (At), for example, is listed as a metalloid in some sources and a nonmetal in others. 

In general, metallic character decreases across a period and increases down a group of the periodic table. Metalloids are elements with properties intennediate between metals and nonmetals. 

Boron is a hard metalloid with pronounced nonmetallic properties. Aluminum is a light, strong, amphoteric, reactive metallic element with a surface that becomes passivated when exposed to air. 

On the other hand, the element with the most nonmetallic properties is fluorine, F. Moreover, the metalloids show either metallic or nonmetallic properties, depending on the conditions. 

Metalloid (semimetal) An element with both metallic and nonmetallic properties. 

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... 

The electronegativity of C is 2.54, as compared with 1.92 for Si. Carbon is strictly nonmetallic whereas Si is essentially a non-metallic element with some metalloid properties. 

Another manifestation of covalent bonding relates to the sulphide mineralogy of the transition elements. Although earlier chapters have stressed properties of transition metal ions in oxides and silicates, an important feature of these elements is the frequency of their geochemical association with B-sub-group non-metal and metalloid elements such as sulphur, selenium, tellurium, phophorus, arsenic and antimony. The chalcophilic properties of iron, cobalt, nickel and copper in the crust are well known and are important eco-... 

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