Metalloids

Metalloids are the elements in the Chemistry Periodic Table whose properties lie in between those of metals and non-metals. All the elements in the periodic table are classified into three categories namely Metals, Non-Metals, and Metalloids. Elements in the periodic table(an arrangement of different elements in order of their increasing atomic number) for the study of their properties, nature, and reaction with other elements.

What are Metalloids?

Metalloids are those elements, that show an intermediate property both of metals and non-metals, present in periodic table. In simple terms, these elements of the periodic table behave both like metals and non-metals. The physical properties and chemical properties of metalloids are intermediate in nature. Their melting point, boiling point, electronegativity, ionization energy, and strength lies between metals and non-metals. Metalloids are generally amphoteric(react both as acidic and basic oxides) in nature. Metalloids have intermediate electrical conductivity.

Metals are the elements that show high density, malleability, ductility, sonorous, lustrous, high strength, and high melting and boiling points. Non-metals are those elements that are less dense, have less boiling and melting points, are not sonorous, not malleable, not ductile, and brittle in nature. Metalloids are those elements that show intermediate properties between metals and non-metals. Metalloids are a little lustrous in appearance, with high melting and boiling points like metals, but are brittle in nature like non-metals.

Which Elements Are Metalloids?

Metalloids, also known as semimetals, are elements that exhibit properties intermediate between those of metals and nonmetals. They typically appear metallic but do not conduct electricity as efficiently as metals, making them useful as semiconductors. The commonly recognized metalloids include:

1. Boron (B)
2. Silicon (Si)
3. Germanium (Ge)
4. Arsenic (As)
5. Antimony (Sb)
6. Tellurium (Te)
7. Polonium (Po)

Some sources also suggest that elements like selenium and astatine may sometimes be classified as metalloids, though this classification can vary. Metalloids are often found along the “staircase” line on the periodic table, which separates the metals from the nonmetals. They are known for their brittle nature and semi-conductive properties, which are crucial in various technological applications such as electronics and optics.

Metalloid Elements in Periodic Table

Metalloid are present from group 13 to group 16 in periodic table in a zig-zag manner . These represent separating the metals and non-metals in periodic table. Metalloids are present in boron family, carbon family, nitrogen family and oxygen family group.

Examples of Metalloids

Examples of metalloid include those element from periodic table which shows both the physical and chemical properties of metals and non-metals. That’s why sometimes metalloid are called as semi-metals or semiconductors. Some of the metalloid present in periodic table are Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium, and Astatine

Metalloid List

The list of Metalloids are mentioned below:

• Boron(B)
• Silicon(Si)
• Germanium(Ge)
• Arsenic(As)
• Tellurium(Te)
• Polonium(Po)
• Antimony(Sb)
• Astatiine(At)

The above mentioned metalloids in chemistry are discussed below in detail

Boron

Boron (atomic number 5) is present in group 13 of periodic table. Boron is solid in nature , has high melting points (2075°C ), and very high boiling point(4000°C), low density and shows very low electrical conductivity. Various usage of boron are as follows:

• Boron are used as cleaning agent, used in washing powders.
• Boron are used in crackers, because it turns into green color while burning.
• Boron are used in manufacturing of fertilizers, mild insecticides and pesticides .

Silicon

Silicon (atomic number 14) is present in group 14 of periodic table. Silicon is second most abundant element present in earth’s crust . Silicon is solid in nature , but brittle in nature has high melting point (1414°C) and high boiling point (3265°C ) , and intermediate electrical conductivity (also known as Semiconductors).

Silicon has numerous applications in medical fields, technical field. In fact without silicon no one can even imagine technological world growing. Various usage of silicon are as follows:

• Silicon are used in computers chips.
• Silicon are used in solar cells, as it is a good semiconductor.
• Silicon are also used to make transistors.

Germanium

Germanium (atomic number 32) is present in group 14 of periodic table. Germanium is lustrous in appearance, but brittle in nature like non-metal . Germanium has a crystalline structure(diamond like structure), with high melting(937°C ) and has high boiling point(2830°C). Various uses of germanium are as follows

• The oxides of Germanium are used in wide-angle camera lenses & objective lenses for microscopes.
• It also acts like semiconductor, same as silicon.
• Germanium is used as infrared detector, because germanium and its oxides are transparent to infrared radiation.

Arsenic

Arsenic (atomic number 33) is present in group 15 of periodic table. Arsenic is crystalline in structure and brittle in nature. It exist in three allotropic form – black, yellow and gray. Arsenic does not have melting point at standard pressure and sublimes from solid to vapor at 615°C. Various uses of arsenic are as follows:

• Arsenic is used as a doping agent in semiconductors.
• Arsenic is added to silicon and germanium to make transistors.
• Arsenic is used in lead alloys for manufacturing of bullets.

Antimony

Antimony (atomic number 51) is present in group 15 of periodic Table. It exist in two forms: one is solid , brittle and silvery bright in appearance and other in gray powder form. The melting point and boiling point of antimony is 630°C and 1,635°C respectively. Antimony is a poor conductor of heat and electricity . Various uses of antimony are as follows:

• Antimony is used in paints and ceramic enamels .
• Antimony was also used as cosmetic in ancient times( by Egyptians) .
• It is used in batteries.

Tellurium

Tellurium(atomic number 52) is present in group 16 of periodic table. Tellurium is a crystalline metalloid which is lustrous in appearance, brittle in nature. The melting point and boiling point of Tellurium is 450°C and 1390°C respectively. Tellurium when inhaled may cause serious health problems which includes drowsiness, metal taste, headache and dry mouth. Various uses of tellurium are as follows :

• Tellurium is used in vulcanization(hardening) of rubber.
• It is used in manufacture of memory chips and solar cells.
• Tellurium was used in treatment of microbial infections before the discovery of antibiotics.

Polonium

Polonium (atomic number 84) is present in group 16 of periodic table. Polonium is highly reactive, silvery gray in appearance. Polonium is a radioactive metalloid. The melting point and boiling point of polonium is 254°C and 962°C respectively. Polonium was discovered by famous scientist Marie Curie and his husband Pierre Curie. Polonium are found in Uranium ores. Various uses of polonium are as follows:

• Polonium is radioactive which emits alpha particles, is used for research purposes.
• It is used as useful source of heat.
• It is used as source of neutrons by mixing it with beryllium.

How Many Metalloids are there on the Periodic Table?

The count of metalloid elements recognized on the periodic table varies significantly, typically ranging from six to eleven, depending on different scientific perspectives.

When Were Metalloids First Used?

Antimony, one of the earliest metalloids recognized, was utilized in ancient Egypt both as cosmetics and as a dye for painting, but it wasn’t formally classified as a metalloid until the 1500s. During the Middle Ages, arsenic gained popularity, likely first isolated by the German physician Albertus Magnus around 1250, and used primarily as a pigment before its toxicity was acknowledged. Silicon, another significant metalloid, was discovered by Swedish chemist Jöns Jacob Berzelius in 1823. The production of commercially available semiconductors began in 1954, marking a significant milestone in technology.

Properties of Metalloids

We know that Metalloid show intermediate properties between metal and non-metal. Hence, we will look at the properties of metalloids below in detail.

• All Metalloids in the Periodic Table are generally solid at room temperature
• Metalloid shows some of the physical properties of the metals such as properties of metals such as some lustrous property used for making alloys and high melting points.
• Metalloid also show some non-metallic properties such as brittle in nature, intermediate ionization energy, and ability to form negative ion.
• The conductivity of metalloid is that between metals and non-metals. Hence, they are extensively used as semiconductors
• The ionization enthalpy and the electronegativity of metalloids are in between the range of metals and non-metals

What Are Metalloids Physical Properties?

Metalloids display physical characteristics that are intermediate between metals and nonmetals. Here’s a key properties:

1. Electrical Conductivity: Metalloids generally have lower electrical conductivity than metals and often exhibit semiconductor properties. This means their ability to conduct electricity can vary based on temperature changes or impurity levels.
2. State at Room Temperature: Metalloids are typically solid when at room temperature.
3. Thermal Conductivity: While metalloids conduct heat more effectively than nonmetals, they are less efficient than metals in this regard.
4. Density: There is considerable variation in the densities of metalloids. For instance, silicon has a density of 2.33 g/cm^3, whereas antimony has a density of 6.69 g/cm^3.
5. Hardness: Metalloids can vary widely in hardness. Arsenic, for example, has a Mohs hardness of 3.5, compared to boron, which has a hardness of 9.3.
6. Mechanical Properties: Generally, metalloids are brittle and have poor ductility, which limits their use in structural applications.
7. Appearance: Many metalloids share a metallic luster, exhibiting shiny, reflective surfaces similar to metals.

These properties make metalloids uniquely useful in various applications, especially in electronics, where their semiconductor capabilities are invaluable.

What Is a Nonmetal?

Nonmetals, as their name implies, are elements that lack metallic characteristics. These elements are typically brittle and are inefficient conductors of heat and electricity. Nonmetals exist both in their pure form and as part of compounds when they combine with other elements.

The periodic table lists 20 nonmetals, divided into three subgroups:

1. Nonmetals: This group includes the more traditional nonmetals such as sulfur, phosphorus, chlorine, and carbon.
2. Halogens: These elements, like silicon, boron, and arsenic, exhibit properties of both metals and nonmetals.
3. Noble Gases: Known for their exceptional stability and lack of reactivity, noble gases such as helium, neon, and argon are also considered nonmetals. Though often categorized separately, they technically fall under the nonmetals category due to their shared chemical non-reactivity.

Metal, Non Metal, and Metalloid

In chemistry, metals are the elements which lose electrons to gain positive charge and they are malleable, ductile and sonrous in nature. On ther other hand, Non-Metals are those elements which gains electrons to gain negative charges on them and their are brittle and non-ductile in nature. In this article, we have seen that metalloids are those elements whose properties lies in between the range of metals and non-metals. All the elements in periodic table can be classified in these three categories only. A detailed comparison between Metal, Non-Metal and Metalloid is tabulated below:

Properties	Metals	Non-metals	Metalloid
Physical Form	solid	solid, liquid or gas	solid at room temperature but easily converted to liquid and gas when heated
Hardness	hard, high durable	soft, brittle material	soft, brittle material
Lustrous	shiny in appearance	Dull in appearance	both shiny and Dull
Heat Conductivity	High	Low	Intermediate
Electrical Conductivity	High	Low	Intermediate
Melting Point	High	Low	Intermediate
Boiling point	High	Low	Intermediate
Density	Highly Dense	Low dense	Intermediate Dense

Properties of Nonmetals

1. Thermal Properties: Nonmetals typically have low melting and boiling points, allowing them to change state from solid to liquid or gas with relatively minimal heat application.
2. Electrical and Thermal Conductivity: Nonmetals are generally poor conductors of both electricity and heat.
3. Mechanical Characteristics: Nonmetals are usually brittle and prone to breaking or shattering under stress.
4. Visual Appearance: Lacking metallic luster, nonmetals usually appear dull and do not reflect light.
5. Density: Compared to metals, nonmetals tend to have lower densities.
6. Physical State Variability: At room temperature, nonmetals can be found in solid, liquid, or gaseous states.
7. Chemical Behavior: Nonmetals commonly gain electrons during chemical reactions, forming negative ions or anions.

These properties make nonmetals distinct from metals and influence their various applications in industries and products.

Examples of Nonmetals

1. Carbon: Used extensively in the production of steel and alloys, carbon is also a key ingredient in the manufacture of various polymers including plastics, resins, and rubber.
2. Chlorine: Employed primarily in water purification, chlorine is also fundamental in producing chemicals like bleach and is used in the manufacturing of plastics and pharmaceuticals.
3. Fluorine: This element is crucial in the production of chemicals such as refrigerants and solvents, and it is also used in pharmaceuticals and added to water supplies to help prevent tooth decay.
4. Hydrogen: Beyond its role as a fuel source, hydrogen is used to produce various chemicals, including ammonia and methanol.
5. Nitrogen: Nitrogen finds extensive use in creating fertilizers and is also involved in the production of explosives and dyes.
6. Oxygen: Essential for life, oxygen is also utilized in various industrial applications, including welding and metal cutting.
7. Phosphorus: Vital for life, phosphorus is used to produce a range of chemicals such as detergents, insecticides, and flame retardants.
8. Sulfur: Used to manufacture fertilizers and sulfuric acid, sulfur plays a critical role in numerous industrial processes.

These nonmetals are integral to various sectors, contributing significantly to modern industrial and healthcare solutions.

What Are Metalloids Chemical Properties?

Metalloids typically exhibit chemical traits more akin to nonmetals. Here’s the common chemical properties:

1. Electronegativity: Metalloids generally have electronegativity values ranging from 1.8 to 2.2, indicating their moderate ability to attract electrons during chemical bonding.
2. Covalent Bonds: Unlike metals, which often form ions, metalloids are more likely to form covalent bonds and do not usually produce monatomic ions.
3. Alloy Formation: Metalloids can be combined with metals to create alloys. For example, antimony is used with lead to produce antimonial lead, which finds applications in ammunition.
4. Chemical Reactivity: Metalloids typically engage in covalent bonding similar to nonmetals and are not prone to forming monatomic anions, a characteristic more common to metals.

These properties highlight the versatile and intermediate nature of metalloids between metals and nonmetals, making them useful in various applications, especially in alloy production and electronics.

Applications of Metalloids

Metalloids have got numerous applications due to properties intermediate to those of metals and non metals. Let’s see some of the applications of metalloids.

• Metalloids are mixed with another elements to form alloys.
• Metalloids can be used for biological purposes such as toxicological substances, medical substances etc.
• Metalloid are used in fireworks as it produces colors when burned like boron produces dark green color.
• Metalloids are used in the production of photovoltaic cells also called solar cells, transistors etc.
• Metalloids are extensively used in semiconductor industry. They used for making computer chips, processors for mobile phone and other parts of electronic devices. Some of the well known semiconductors used in the electronics industry are Si, Ge, GaAs etc.

Metalloid – FAQs

What are metalloids?

Metalloids are chemical elements that exhibit properties intermediate between metals and non-metals. They are also known as semimetals​.

Which elements are considered metalloids?

The commonly recognized metalloids include boron, silicon, germanium, arsenic, antimony, and tellurium. Some sources also include elements like polonium and astatine under certain conditions​​.

Where are metalloids located on the periodic table?

Metalloids are located along the zig-zag line that divides metals and nonmetals on the periodic table, generally found in the p-block.

What are the general properties of metalloids?

Metalloids typically appear metallic but are brittle and have poor thermal and electrical conductivity compared to metals. They are good semiconductors and often exhibit amphoteric oxide formation​.

What are the typical uses of metalloids?

Metalloids are used in a variety of applications including in semiconductors, electronics, alloys, catalysts, flame retardants, and optical storage devices due to their unique electrical properties​​.

How do metalloids behave chemically?

Chemically, metalloids can behave like nonmetals. They can form covalent bonds and often have intermediate electronegativity and ionization energies.

What are the crystal structures of metalloids like?

Metalloids like silicon and germanium crystallize in a diamond structure, while arsenic and antimony have layered structures, and tellurium forms spiral chains of atoms.

How do the electrical properties of metalloids impact technology?

The semiconductor properties of metalloids like silicon and germanium have been crucial for the development of the semiconductor industry, impacting everything from computers to solar cells​.

What are the differences between metalloids and other elements?

Metalloids differ from metals and nonmetals primarily in their electrical conductivity, which is higher than nonmetals but lower than metals. They are less malleable than metals and do not exhibit the high reactivity of many nonmetals.

Why are metalloids important in materials science?

Their ability to conduct electricity only under certain conditions makes metalloids valuable for making transistors and diodes, which are essential components of many electronic devices​.

Is Aluminum a Metal or Metalloid?

Aluminum is metal, because it is ductile, lustrous, malleable, and it has high melting and boiling point.

Is Polonium a Metalloid?

Yes, Polonium is a metalloid.

Is Arsenic a Metalloid?

Yes, Arsenic is a metalloid because it shows intermediate properties between metals and non-metals.

Is Germanium a Metalloid?

Yes, Germanium is a metalloid and widely used in semiconductor industry