Reactivity of Boron & Aluminium

Introduction

• Group 13 elements are known as p-block elements.
• Boron (B) and Aluminium (Al) are the two most commonly studied elements of Group 13.
• These elements exhibit unique reactivity patterns.
• In this lecture, we will focus on the reactivity of Boron and Aluminium.

Reactivity of Boron

• Boron is a metalloid and its atomic number is 5.
• It has a low reactivity due to its small atomic size.
• Boron usually forms compounds by accepting or sharing electrons.
• Boron reacts with halogens to form halides, such as boron trifluoride (BF3). Example: BF3 B + 3F → BF3
• Boron also forms compounds with oxygen and hydrogen.

Reactivity of Aluminium

• Aluminium is a metal with atomic number 13.
• It has a higher reactivity compared to Boron.
• Aluminium primarily forms compounds by donating its three valence electrons.
• It reacts with halogens to form aluminum halides, such as aluminium chloride (AlCl3). Example: AlCl3 ``

2Al + 3Cl2 → 2AlCl3 ``

• Aluminium also reacts with oxygen, forming aluminum oxide (Al2O3), which has many practical applications. Example: Al2O3 ``

4Al + 3O2 → 2Al2O3 ``

• Aluminium can also react with acids and bases.

Reactivity Comparison

• Boron has lower reactivity compared to Aluminium.
• Boron forms covalent compounds while Aluminium forms ionic compounds.
• Boron generally only accepts or shares electrons, while Aluminium primarily donates electrons.

Applications of Boron and Aluminium

• Boron compounds are used as catalysts in various chemical reactions.
• Aluminium is widely used in industries, such as construction, packaging, and transportation, due to its low density and high strength.
• Aluminium alloys are commonly used in aircraft manufacturing.

Summary

• Boron and Aluminium are Group 13 elements with different reactivity patterns.
• Boron has low reactivity and forms covalent compounds.
• Aluminium has higher reactivity and primarily forms ionic compounds.
• Both elements find various applications in different industries.

Key Points to Remember

• Boron is a metalloid with low reactivity.
• Aluminium is a metal with higher reactivity compared to Boron.
• Boron forms covalent compounds, while Aluminium forms ionic compounds.
• Boron and Aluminium have different practical applications.

11. Boron Electronegativity

• Electronegativity is the measure of the tendency of an atom to attract a bonding pair of electrons.
• Boron has an electronegativity value of around 2.04.
• This moderate electronegativity contributes to Boron’s ability to accept or share electrons with other elements.
• Examples: BF3, B2H6

12. Aluminium Electronegativity

• Aluminium has an electronegativity value of around 1.61.
• This moderate electronegativity also allows Aluminium to donate electrons in chemical reactions.
• Examples: AlCl3, Al2O3

13. Boron Hydrides

• Boron forms hydrides, compounds consisting of Boron and Hydrogen.
• Two common examples are diborane (B2H6) and borane (BH3).
• Diborane has a bridged structure and is used as a reducing agent in various chemical reactions.
• Borane is highly reactive and readily forms complexes with Lewis bases.

14. Aluminium Halides

• Aluminium reacts with halogens to form different halides.
• Aluminium chloride (AlCl3) is a commonly studied example.
• It has a planar structure and is used as a catalyst in various organic reactions.
• Aluminium iodide (AlI3) is another example and is used in the synthesis of organic compounds.

15. Boranes and Diboranes

• Boranes and diboranes are important compounds of Boron.
• These compounds have boron-hydrogen bonds and contain boron in lower oxidation states.
• Boranes and diboranes are often used as reducing agents, catalysts, and in the synthesis of pharmaceuticals and polymers.

16. Aluminium Oxides

• Aluminium reacts with oxygen to form different oxides.
• Aluminium oxide (Al2O3), also known as alumina, is a widely used oxide.
• Alumina has high heat resistance and is an important component of ceramics and refractories.
• It is also used in the production of aluminium metal.

17. Borates

• Borates are compounds that contain the borate ion (BO3) and other elements.
• Sodium borate, commonly known as borax, is an important borate compound.
• It is used in the manufacturing of glass, soaps, and detergents.
• Borates also have applications in agriculture as fertilizers and wood preservatives.

18. Reactions with Acids

• Boron and Aluminium both react with acids.
• Boron reacts with strong acids, such as hydrochloric acid, to form boric acid.
• Aluminium reacts with dilute acids, such as hydrochloric acid, to form aluminium chloride and hydrogen gas.

19. Reactions with Bases

• Both Boron and Aluminium react with bases.
• Boron reacts with strong bases, such as sodium hydroxide, to form borates.
• Aluminium reacts with bases, such as sodium hydroxide, to form aluminates.

20. Use of Boron and Aluminium in Industries

• Boron compounds are used in the production of fiberglass, detergents, and flame retardants.
• Aluminium is widely used in industries like automotive, construction, and packaging.
• Aluminium alloys are used in the manufacturing of aircraft, cars, and cans.
• The unique properties of Boron and Aluminium contribute to their wide applications in various industries.

21. Industrial Uses of Boron

• Boron compounds are used in agriculture as micronutrient fertilizers.
• Borosilicate glass, which contains boron, is used in laboratory equipment and glassware.
• Boron compounds are used in the production of neodymium magnets.
• Boron is used in the production of high-energy fuels for rockets.
• Boron fibers are used in the manufacturing of lightweight and strong composites.

22. Boron Nitride

• Boron nitride (BN) is a compound made of boron and nitrogen.
• It has a similar structure to carbon graphite and exhibits high thermal conductivity.
• Hexagonal boron nitride (h-BN) is used as a lubricant due to its low friction properties.
• Cubic boron nitride (c-BN) is one of the hardest known materials and is used in cutting tools and abrasives.

23. Aluminium Compounds

• Aluminium compounds have various applications in industries and daily life.
• Aluminium sulfate (Al2(SO4)3) is used in water treatment and paper manufacturing.
• Aluminium hydroxide (Al(OH)3) is used in antacids and as a filler in rubber and plastics.
• Aluminium acetate (Al(C2H3O2)3) is used in medical treatments for skin conditions.
• Aluminium phosphide (AlP) is used as a fumigant for stored grain to control pests.

24. Aluminium Alloys

• Aluminium alloys are formed by mixing pure aluminium with other elements.
• Aluminium alloys have enhanced strength, durability, and corrosion resistance.
• Examples of aluminium alloys include 6061-T6 (commonly used in structural applications) and 7075-T6 (used in aerospace applications).
• The addition of alloying elements, such as copper, magnesium, and zinc, allows for customization of the alloy’s properties.

25. Aluminium Recycling

• Aluminium is highly recyclable and can be recycled indefinitely without loss of quality.
• Recycling aluminium consumes around 5% of the energy required to produce primary aluminium.
• Recycling aluminium reduces the need for mining new bauxite ore and helps conserve natural resources.
• The recycling process involves melting down used aluminium products and reforming them into new products.

26. Boron and Aluminium Toxicity

• Boron and aluminium, in high concentrations, can be toxic to plants and animals.
• High boron concentrations in water can affect human health and cause respiratory and gastrointestinal issues.
• Aluminium toxicity affects the growth and development of plants and can lead to soil acidification.
• Proper management and monitoring of boron and aluminium concentrations are essential to avoid environmental and health issues.

27. Boron and Aluminium in Biological Systems

• Boron plays a crucial role in the growth and maintenance of bone and joint health.
• Aluminium accumulated in the body can have detrimental effects, including neurotoxicity.
• Research is being conducted to understand the impact of boron and aluminium on human health and develop strategies to minimize toxicity.

28. Boron and Aluminium in the Environment

• Boron occurs naturally in rocks, soil, and water, but its concentration varies geographically.
• Aluminium is the most abundant metal in the Earth’s crust and is found in many minerals.
• Both elements can be released into the environment through natural weathering processes and human activities.
• Monitoring the levels of boron and aluminium in different environmental compartments is important for assessing their impact on ecosystems.

29. Recent Advances in Boron and Aluminium Chemistry

• Researchers are exploring new synthetic methods for boron-based polymers with unique thermal and electrical properties.
• Novel aluminium-based catalysts are being developed for more efficient and sustainable chemical reactions.
• Advances in boron and aluminium chemistry contribute to the development of technologies in various sectors, including energy storage, medicine, and materials science.

30. Summary and Conclusion

• Boron and aluminium exhibit distinct reactivity patterns, with boron being less reactive than aluminium.
• Boron forms covalent compounds, while aluminium primarily forms ionic compounds.
• Both elements have a wide range of applications in various industries, including construction, aerospace, and electronics.
• Proper management and understanding of the toxicity and environmental impact of boron and aluminium are essential.
• Ongoing research in boron and aluminium chemistry is driving advancements in various fields, contributing to the development of new technologies.