Boron: A Metalloid Of Vital Importance

Nov 7, 2021 | SCIENCE

Boron: A Metalloid

Boron is a metalloid element found in meteoroids, precious minerals, and diamonds. It’s not naturally present on Earth; however, it can be produced through complex processes that involve removing contaminants such as carbon from other elements.



Boron powder does not count as a metal. Furthermore, Boron is considered a solid non-metal since it lacks the general characteristics of metals. It is the only element with a layer at its outermost of less than 4 electrons. Also, boron is a non-metal with a low concreteness that forms covalent bonds to other non-metallic substances.

Boron is found in crystalline and amorphous forms. The first is a brown-black-black powder, and the other is silver-gray-black. It has a metallic shine and is very similar to a diamond in hardness.

 Amorphous Boron slowly oxidizes in the air at room temperature and self-ignites at 800 degrees Celcius. Boron and hydrochloric or hydrofluoric acids will not work if the items are boiled for long periods.

Crystal Boron

Because it is difficult to prepare pure Boron, elemental Boron is very rare and poorly studied. However, studies of “boron” are limited to samples with small amounts of carbon. Boron’s chemical behavior and properties are similar to silicon but more than aluminum

Crystalline Boron can be heated in hydrofluoric or hydrogen chloric to make it chemically inert. It is slowly attacked by hot concentrated hydrogen peroxide or hot sulfuric acids.

High-purity boron can be found as an amorphous dark brown or black powder or a dark, lustrous, brittle crystal metal.

Boron is extremely hard and resists heat. However, it is a poor conductor of electricity at low temperatures. This changes with increasing temperatures. Crystalline Boron is stable and does not react with acids. However, the amorphous version can respond violently to acid and slowly oxidize.

Boron is the most challenging element in crystalline form (behind carbon in its diamond form). It also has the highest melting temperatures. Early scientists often mistook Boron for carbon, but Boron forms a stable covalent bond that makes it difficult to isolate.

Found in nature as boric acid or borate minerals such as Borax, this metalloid has many applications in modern industry, ranging from plastics to fertilizers.

Boron’s Electron Configuration

It has an atomic number of 5, which means it is part of Group IVA on our periodic table. Boron’s chemical symbol, B, is a silvery-white solid at room temperature. When hot, boron is malleable and soft. It hardens to a brittle substance when cooled.

Boron’s electronic configuration can be described as 2s2p3d5, in which s stands to represent “silicon” while p stands to represent “phosphorus.” Boron is a tetravalent metalloid.

All metalloids are the first three elements on the right side of the Periodic Table: silicon, germanium, and tin. These elements can form compounds with oxygen and nitrogen as well as sulfur. These elements are known as oxides, nitrides, and sulfides. Boron, on the other hand, can only form compounds with itself.

Properties of Boron Metalloid

The oxidation rate depends on crystallinity, size of particles, purity, temperature, and other factors. Boron doesn’t react with air at room temperature but forms boron trioxide at higher temperatures.

Model of the tetraborate anion in ball-and-stick form, [B4O5OH]4]2-, as found in crystal borax, Na2[B4O5OH)4]*8H2O. The atoms of Boron are pink with four hydroxyl hydrogens and bridging oxygens red. Two borons have a trigonally bonded sp2 without formal charge.

The other two borons have a tetrahedrally bound sp3, each with a standard charge of -1. All borons have an oxidation status of III. This combination of formal charges and boron coordination numbers is typical of natural minerals.

Boron is halogenated to produce trihalides, such as

2 B + 3 Br2 = 2 BBr3

In practice, trichloride is made chiefly from oxide.

Modern Industrial Usage of Boron Metalloid

Boron metalloid is an incredibly versatile element that has a wide range of applications. From the late 1800s, it was used to create stable and durable materials such as Pyrex glass. Following World War II, this elemental metal found a variety of applications – from cosmetics to control rods for nuclear reactors.

In 1986 it even helped avert disaster when authorities dumped 40 tonnes of Boron compound on a reactor to prevent radionuclide release.

In more recent years, however, boron metalloid has been used extensively in the production of high-strength rare earth magnets, i.e., neodymium iron boron (NdFeB magnets), with over 70 metric tons produced each year across industries worldwide.

In automobiles, this metalloid was used to strengthen structural elements such as safety bars in the 1990s.

Borate Minerals

There are over 200 types of borate minerals in the Earth’s crust. However, only four account for more than 90 percent of commercial extraction of boron or boron compounds – Tincal, Kernite, Colemanite, and Ulexite.

The boron oxide in the minerals is heated with aluminum or magnesium flux to produce a pure form of Boron. This reduces the elemental boron powder to a level of approximately 92 percent.

You can make pure Boron by reducing the boron halides and hydrogen at temperatures above 1500 C (2732 F).

You can make high-purity Boron for semiconductors by melting diborane at high temperatures and growing single crystals using zone melting or the Czolchralski process.

These are the primary uses and production methods.

Fireworks: This is the most explosive way to use a metalloid. Boron is a popular choice for fireworks and pyrotechnics because of its bright green color. Borax or boric acid can be mixed with methanol to create a green flame and lit it.

Cleaning: There is probably some borax or boric acids in your garage or kitchen. This famous cleaning agent can be used for pest control and is non-toxic.

Bakeware: Pyrex is a famous brand of glass bakeware. You may have one in your kitchen. If not, you are using another type of Boron. Pyrex used borosilicate glasses, which are durable and resist thermal shock. Borosilicate glass is a mixture of the first two elements from our list, Boron, and silicon.

Although metallic Boron is rarely used, it has many metallurgical uses. A tiny amount of Boron can be added to steel to make it stronger than average high-strength steel by removing carbon and other impurities.

Its ability to dissolve and remove oxide metal makes it ideal for welding fluxes. Boron trichloride can remove nitrides and carbides from molten steel. Boron trichloride can be used to make aluminum and magnesium. Zinc and copper alloys are also made.

The presence of metal borides in powder metallurgy increases conductivity and mechanical strength. Their presence in ferrous products increases corrosion resistance and hardness, and in titanium alloys used for jet frames and turbine parts, they increase mechanical strength.

Boron fibers are created by depositing the element of hydride on tungsten wire. They are solid and light structural materials used in aerospace applications, golf clubs, or high-tensile tape.

NdFeB magnets must contain Boron to function appropriately in high-strength permanent magnetics. These magnets are used in electric motors, wind turbines, and various electronic devices. The third most difficult known substance, Boron carbide, can make armor, bulletproof vests, abrasives, and wear parts.