What are Metalloids?

Metalloids can be defined as chemical elements whose physical and chemical properties fall in between the metal and non-metal categories. Boron, germanium, silicon, antimony, arsenic, tellurium and pollanium are the seven most widely recognized metalloids.

It can be noted that all seven of these elements can be found on the regular periodic table in a diagonal region of the p-block which extends from boron (which is placed on the upper left) to astatine (which is placed on the lower right). Some periodic tables have a dividing line between metals and nonmetals, and below this line, the metalloids can be found.


Typically, metalloids have metallic appearances but they are usually brittle and only mediocre electricity conductors. Chemically, these elements usually behave as non-metals. Metalloids have the ability to form metallic alloys. Other physical properties and chemical properties of the metalloid elements are usually intermediate in nature. In general, these elements are extremely fragile and, therefore, do not have many structural applications. In alloys, catalysts, biological agents, glasses, flame retardants, optical storage and optoelectronics, semiconductors, pyrotechnics, and electronics, Metalloids and their compounds are used.

Table of Contents

General Properties of Metalloids

  • Metalloids typically look like metals. However, these elements often behave like non-metals.
  • Physically, metalloids are brittle, somewhat shiny substances that are usually solid at ambient temperatures.
  • These elements usually have intermediate to fairly strong electrical conductivity
  • Metalloids are known to have electronic band structures that are similar to semimetals or semiconductors.
  • Chemically, these elements usually act as non-metals (in a relatively weak manner)
  • These elements generally have intermediate energies of ionisation and values of electronegativity
  • Metalloids are known to form amphoteric or weakly acidic oxides.
  • These elements have the ability to form metallic alloys.
  • Many of the other physical and chemical properties of metalloids, in essence, are intermediate.

Applications of Metalloids

Metalloids and the compounds of metalloids are widely used as alloys (or in the production of alloys as a component of the mixture), biological agents (which can be nutritional, toxicological, and medicinal as well), flame retardants, catalysts, glasses (which can be oxides or metallic in nature), and optical storage media. Metalloids are also known to have applications in optoelectronics, semiconductors, pyrotechnics, and electronics.

Alloys formed when combined with transition metals are extremely well-represented when it comes to the lighter metalloids. Boron has the ability to form intermetallic compounds. This element also has the ability to form alloys with these MnB composition metals if the value of n is greater than 2. In fact, ferroboron (which contains 15 per cent boron) is widely used in order to inject boron into steel. Furthermore, nickel-boron alloys are used as ingredients in the engineering industry for welding alloys and case hardening compositions.

Silicon alloys of aluminium and iron are widely used in the construction and automotive industries. Germanium is known to form several alloys, especially the coinage metals in particular.

Medical Applications of Metalloids

Each and every one of the six elements that are widely known as metalloids are known to be either toxic, or to have medicinal and nutritional properties. For example, compounds of antimony and arsenic are known to be especially toxic. However, boron, arsenic, and silicon are extremely important trace elements.The four elements boron, arsenic, silicon, and antimony are known to have many medical uses. The remaining two elements (germanium and tellurium) are known to have great potential for medicinal applications.

Furthermore, boron is used in herbicides and also in insecticides. This element is an active trace element, which has several antiseptic, antiviral, and antifungal properties in the form of boric acid.

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Frequently Asked Questions on Metalloids


What are the 8 elements that are collectively referred to as metalloids?

The elements which are found in the step-like line between metals and nonmetals of the periodic table are known as the metalloids. They are: antimony (Sb), germanium (Ge), silicon (Si), arsenic (As), tellurium (Te), polonium (Po), boron (B), and astatine (At).


What is the definition of the term ‘metalloid’?

A metalloid is a chemical element that exhibits some metal and some nonmetal properties. Metalloids form a jagged region in the periodic table separating elements which have clear metallic properties from elements which have clear non-metallic properties.


How can metalloids be identified?

The easiest way to decide if a given unknown element is a metalloid is by testing whether any metal and non-metal characteristics can be detected. If both are detected, then the given element is most likely to be a metalloid element.


Can mercury be classified as a metalloid?

No, mercury can not be classified as a metalloid. Having a valency of 1or 2, the element known as mercury must be classified as a metal. This is because this element conducts electricity and is also a very good conductor of heat.


What are the common properties of metalloids?

Metalloids are good semiconductors.
The reactivity of metalloids is dependent on the properties of the elements they are reacting with.
Electronegativity and ionisation energy are between metals and nonmetals.
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