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What are Metalloids?

Metalloids definition can be given as a type of chemical element which contains a preponderance of properties in between, or it can be defined as a mixture of both metals and nonmetals. Also, there is no standard definition to describe a metalloid and non compete agreement, where the elements are metalloids. Despite the absence of specificity, the word remains in use in the literature of chemistry.

About Metalloid

The six commonly recognized metalloids are given as silicon, boron, arsenic, germanium, tellurium, and antimony. On the other side, five elements are classified less frequently: aluminium, carbon, polonium, astatine, and selenium. In the standard periodic table, all the eleven elements are present in a p-block's diagonal region by extending from boron at the upper left to astatine at the lower right position. A few periodic tables include a dividing line between the metals and nonmetals, and metalloids can be found close to this line.

The typical metalloids have a metallic look, but they are brittle and only good conductors of electricity. Chemically, they are often nonmetals. They have the ability to create metal alloys. In nature, the majority of their other physical and chemical properties are intermediate. Usually, metalloids are too brittle to hold any structural uses. Including their compounds, they are used in biological agents, alloys, flame retardants, catalysts, optical storage, glasses, pyrotechnics, electronics, and semiconductors.

Periodic Table Territory

Metalloids lie on the dividing line's either side between both metals and nonmetals. This may be found, in differential configurations, on a few periodic tables. In general, elements to the upper right exhibit increasing non-metallic behavior, and elements to the lower left of the line exhibit increasing metallic behavior. When they are presented as a regular stair step, the elements having the highest critical temperature for their groups (Be, Li, Ge, Al, Sb, and Po) lie just below the line.

Alternative Treatments

Metalloids are not often classified as elements near the metal-nonmetal dividing line; note that a binary classification can make it easier to define rules for defining bond forms between metals and nonmetals. In those cases, the authors were more focused on either one or more attributes of interest to make their classification decisions instead of being concerned about the marginal nature of the elements.

Properties of Metalloids

Usually, metalloids look similar to metals, but they behave largely similar to nonmetals. Physically, they are brittle and shiny solids with an intermediate to relatively good electrical conductivity and the electronic band structure of either semiconductor or semimetal. Whereas, chemically, they behave mostly as weak nonmetals, which have intermediate electronegativity and ionization energy values, and weakly or amphoteric acidic oxides. They can produce alloys with metals. Most of the metalloid’s other physical and chemical properties are intermediate in nature.

Common Applications

Metalloids are more brittle to hold any structural uses in their pure forms. Their compounds, including them, can be used as alloying components, biological agents (nutritional, medicinal, and toxicological), flame retardants, catalysts, glasses (both oxide and metallic), optoelectronics, and optical storage media, semiconductors, electronics, and pyrotechnics.


Writing early in the intermetallic compound history, the British metallurgist Cecil Desch noticed that "certain non-metallic elements are able to form distinctly metallic character compounds with metals, and these particular elements can therefore enter into the composition of alloys". He associated arsenic, tellurium, and silicon, in particular, with the alloy-forming elements. Williams and Phillips suggested that the compounds of germanium, silicon, antimony, and arsenic with B metals "are probably the best alloys".

Biological Agents

Commonly, all the six elements are recognized as metalloids containing dietary, medicinal, or toxic properties. Antimony and arsenic compounds are especially toxic; silicon, boron, and possibly arsenic are the important trace elements. Silicon, boron, antimony, and arsenic have medical applications. At the same time, tellurium and germanium are thought to have potential.


Trichloride and boron trifluoride can be used as catalysts in electronics and organic synthesis; the tribromide can be used in diborane manufacturing. Also, the non-toxic boron ligands could replace the toxic phosphorus ligands in a few transition metal catalysts. Silica sulfuric acid - SiO2OSO3H can be used in organic reactions. Sometimes, germanium dioxide can be used as a catalyst in the PET plastic formation for containers; cheaper antimony compounds, such as triacetate or trioxide, are more commonly employed for a similar purpose, despite the concerns on antimony contamination of drinks and food.

Flame Retardants

Compounds of silicon, boron, antimony, and arsenic have been used as flame retardants. In the form of borax, boron has been used as a textile flame retardant since the 18 century, at least. Whereas silicon compounds such as silanes, silsesquioxane, silicones, silicates, and silica, some of which were developed as alternatives to more products of a toxic halogenated type, can considerably improve the retardancy flame of plastic materials.

Glass Formation

The oxides SiO2, B2O3, Sb2O3, and As2O3 readily make glasses. Also, TeO2 makes a glass, but this needs the addition of an impurity or a "heroic quench rate"; otherwise, it results in the crystalline form. These compounds can be used in domestic, industrial, and chemical glassware and optics. On the other side, boron trioxide can be used as a glass fibre additive and also as a borosilicate glass component, which can be widely used for domestic ovenware and laboratory glassware for its low thermal expansion.

FAQ (Frequently Asked Questions)

1. Explain the Use of Metalloids on Optical Storage and Optoelectronics?

Answer: Varying compositions of Ag-, In- doped Sb2Te ("AIST alloys"), and GeSbTe (which is "GST alloys"), being examples of phase-change materials, can be widely used in the phase-change memory devices and rewritable optical discs. They can be switched between crystalline and amorphous (glassy) states by applying heat.

2. Explain the Origin of Metalloids?

Answer: The origin of the term metalloid can be convoluted. Its origin exists in attempts, dating from antiquity, to define the metals and to vary between less typical and typical forms. First, it was applied in the early 19 century to the metals, which floated on water (potassium and sodium), and then to more popularly nonmetals. Earlier usage in the mineralogy, to define a mineral containing a metallic appearance, is sourced to as early as 1800.

3. Give One Commonly Used Recognized Metalloid?



Pure boron is given as a silver-grey and shiny crystalline solid. It is less dense compared to aluminium (2.34 vs. 2.70 g/cm³) and is brittle and hard. It can be barely reactive under certain normal conditions, except for fluorine attack, and contain a melting point of 2076 °C.

4. Give One Metalloid, Which is Less Commonly Recognized?



Carbon can be ordinarily classified as a nonmetal but has a few metallic properties, and occasionally, it is classified as a metalloid. Hexagonal graphitic carbon (otherwise called graphite) is the most thermodynamically stable allotrope of carbon under ambient conditions. It contains a lustrous appearance and a fairly good electrical conductor.