Boron: The Element

Boron is a chemical element having the symbol B and atomic number 5. It is found in abundance in borax, colemanite, ulexite, kernite, borates and boric acid. Natural boron comprises 19.78% of boron -10 and 80.22% of boron -11. Some allotropes of boron are amorphous boron, crystalline boron and elemental boron.

Boron derives its name from 'buraq', the Arabian word for the mineral Borax. Although it was known for thousands of years, boron was recognized as as element only in 1808, when it was isolated by British chemist, Sir Humphry Davy and French chemists, Joseph Louis Gay-Lussac and Louis Jacques Thénard. Pure boron was produced for the first time in 1909, by an American chemist W.Weintraub.

Occurrence

One of the rarest elements, it makes up only 0.001% of the Earth's crust. It is estimated that the worldwide borate deposits account for about 10¹⁰ kg. Turkey and United States are the leading producers of boron in the world, with Turkey being home to around 72% of the boron reserves on the planet. Kernite and borax ore are found in abundance in the Mojave Desert of California. Balikesir, Kutahya and Eskisehir provinces of Turkey have some of the largest borax deposits in the world.

Characteristics

• The melting point of boron is 2079° C, while its boiling point is 2550° C.
• The specific gravity of amorphous boron is 2.37, while that of crystalline boron is 2.34.
• Although a poor conductor of electricity at room temperature, boron is a good conductor at high temperatures.
• This chemical element is capable of forming stable covalently bonded molecular networks.
• Crystalline boron is a hard material, black in color, and has a very high melting point. It exists in four major polymorphs, namely α, ß, γ and T.
• At room temperature, boron doesn't react with air, but at higher temperatures boron burns to form an oxide of boron, called boron trioxide.
• The boron hydrogen compounds are highly flammable and thus need to be handled with utmost care.
• Boron halides are corrosive in nature.
• Chemically inert in nature, crystalline boron is resistant to attacks by hot hydrochloric acid or hydrofluoric acid. However, it is vulnerable to attacks of hot concentrated hydrogen peroxide, nitric acid and sulfuric acid.
• It is very difficult to obtain boron in its purest form because the end product is always contaminated with metal borides.
• In order to obtain boron in the most possible pure form, the volatile boron halides in the product have to be reduced, using hydrogen at high temperature.
• Pure boron is also obtained by decomposing diborane, a chemical compound comprising of boron and hydrogen, at high temperatures and then purifying it with zone melting.

Uses

• In the United States of America, 70% of the boron produced is used in the manufacture of glass and ceramics.
• It acts as a technological dopant in semiconductors, like silicon, silicon carbide and germanium.
• Compounds of boron, like boron carbide and boron nitride, are used in industrial applications.
• Boron carbide is also used in defense equipments, such as bullet proof vests and tank armors.
• In nuclear power plants, boron is used as an absorbent for neutron radiation.
• The light but strong boron filaments are used to build aerospace structures.
• It is used in plastic and rubber materials to make them fire retardant.
• Boron carbide and boron nitride are also used as abrasives.
• Boric acid is used for water treatment in swimming pools and as an insecticide against cockroaches and ants.
• It is one of the essential micro-nutrients required for proper growth in plants.

This element is non-toxic to humans and animals, unless it is consumed in large amounts. With its multiple uses, boron is an element which is helpful to mankind.