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The Compounds of Boron are borax, orthoboric acid and boron hydrides. Boron is identified as a chemical element that has an atomic number of five. Boron is a trace element generally found in the earth’s crust and solar system. It is also a type of metalloid. Boron belongs to the Group-13 elements of the p-block in the modern periodic table. The electronic configuration of Boron is [He]2s22p1. The pure black form of the crystalline boron is usually lustrous and acts as a semiconductor. Boron has a Melting point of 2,200°C (4,000 °F), and a Boiling point of 2,550°C (4,620 °F).
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Key Terms: Boron, P-block Elements, Periodic Table, Atomic Number, Electronic Configuration, Borax, Orthoboric Acid, Boron Hydrides
What is Boron?
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Boron belongs to the Group-13 elements of the p-block in the modern periodic table. It is a chemical element with an atomic number of five. Boron is considered as a non metallic element in the periodic table.
Boron
It is also the only non-metal of group-13 of the periodic table. Boron is a chemical element which is both electron-deficient and has a vacant p-orbital. Boron typically has numerous forms, out of which the most common is amorphous boron (i.e., a dark powder which does not react to oxygen, water, acids and alkalis.)
Read Also:
| Topic Related Links | ||
|---|---|---|
| Group 14 Elements | Group 15 Elements | Diborane |
| Silicates | Allotropes of Carbon | Boric Acid |
Compounds of Boron
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There are several compounds of Boron. Some of them include:
- Borax
- Orthoboric Acid
- Diborane
Borax
Borax is a white crystalline solid structure with a formula of Na2B4 O7.10H2O.. However, the actual formula of borax is, Na2[B4 O5(OH)4].8H2O. When Borax is dissolved in water, it gives an alkaline solution. The alkaline solution is sodium borate and orthoboric acid.
Borax
| Na2B4O7 + 7H2O → 2NaOH + 4H3BO3 (Orthoboric acid) |
If heated, borax loses water and results in swelling of molecules. Upon further heat, it turns into a glassy structure, forming a borax bead. On initial heating, it produces sodium metaborate, while if heated again, it produces sodium anhydride. Metaborates of transition metals typically have their own characteristic colour, thus borax bead test can be utilised in lab. For example, if borax is heated around CoO on a platinum wire, a blue bead forms.
Orthoboric Acid
Orthoboric acid has a chemical formula of H3BO3 and has a white crystalline solid structure which is soapy when touched. Orthoboric Acid is sparingly soluble in water but dissolved well in hot water. Boric acid typically functions as a Lewis acid via accepting electrons from hydroxyl ion.
Orthoboric Acid Structure
Diborane
Diborane has a molecular formula of B2H6. When boron trifluoride reacts with LiAlH4 in diethyl ether, it forms diborane. Diborane is typically colourless and toxic. It comes with a boiling point of 180 K.
Diborane Structure
| 4BF3 + 3LiAlH4 → 2B2H6 + 3LiF + 3AlF3 |
Diborane can catch fire very easily, releasing a large amount of energy. After reacting with Lewis bases, it experiences a cleavage reaction which produces boron adducts.
Manufacturing of Boric AcidFrom Borax If Borax reacts either with Hydrochloric acid (HCl) or Sulphuric acid, it forms Boric acid. Once done, the mixture is cooled to obtain the white powdery pieces of Boric acid. By the Hydrolysis Process of Compounds of Boron Boron nitrides, boron sulfides, boron halides and more undergo the process of hydrolysis which helps procure the product, named Boric Acid. |
Properties of Boron
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There are several properties of Boron. Some of them include:
- A pure crystalline boron structure is usually black in colour and is a lustrous semiconductor.
- Boron is soluble in cold water (only to some extent). However, when mixed with high-temperature water, it breaks down.
- The alkaline nature of the Boric Acid solution makes it a very feeble acid.
- In higher temperatures, it behaves like a metal and conducts electricity. While, it functions as an insulator in low temperatures.
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Things to Remember
- Boron is a chemical element that has an atomic number of five.
- Boron is found in the Group-13 elements of the p-block in the modern periodic table.
- It is simply both electron-deficient and has a vacant p-orbital. Boron has various forms, out of which the most common is amorphous boron.
- Some of the major compounds of Boron are Borax, Orthoboric Acid, and Diborane.
Sample Questions
Ques. What is Boron? (2 marks)
Ans. Boron is a chemical element in the modern periodic table that has the symbol B and atomic number of 5. In the crystalline form of Boron, it is found to be brittle, dark, and as a lustrous metalloid. The electronic configuration of Boron is [He]2s22p1. The pure black form of the crystalline boron acts as a semiconductor. Boron has a Melting point of 2,200°C (4,000 °F), and a Boiling point of 2,550°C (4,620 °F).
Ques. What are some uses of Boric Acid? (5 marks)
Ans. Some of the major uses of Boron are:
- Like Borax, boric acid is also used for the manufacture of enamel and ceramics coats.
- It is used for the synthesis of borax and other pigments.
- Boric Acid is often used in form of eyewash.
- Boric acid also asts as a food preservative in the industry.
- Helps in the manufacturing of borosilicate glass.
Ques. What are the compounds of Boron? (3 marks)
Ans. The three compounds of Boron are:
- Borax
- Orthoboric Acid
- Diborane
Ques. Show happens when borane is hydrolysed. (2 marks)
Ans. When hydrolysed by water, Boranes give Boric Acid as a result. The following reaction demonstrates the same:
B2H6(gas) + 6H2O(liquid) → 2B(OH)3(aq) + 6H2 (gas)
Ques. Why is boric acid regarded as a weak acid? (2 marks)
Ans. Boric acid is considered a weak acid because it cannot release H+ ions on its own. It usually takes OH- ions from water, following the completion of its octet, it then releases H+ ions.
Ques. What are some uses of Diborane? (3 marks)
Ans. Some of the major uses of Diborane are:
- Diborane can be used in the vulcanisation of rubber.
- Used for rocket propellants.
- Acts as a catalyst in several polymer reactions.
Ques. Is borax basic or acidic in nature? (2 marks)
Ans. When dissolved in water, Borax yields an enormous amount of Hydroxide ions in the form of Sodium hydroxide. Therefore, it hides the acidity of the orthoboric acid. hence, borax in basic in nature and has a pH of 9.13.
Ques. What are Group 14 elements? Name the elements in found in Group 14. (3 marks)
Ans. The group 14 elements, otherwise called the carbon group, are considered as the second group in the p-block of the periodic table. The members of the carbon group are as follows:
- Carbon (C)
- Silicon (Si)
- Germanium (Ge)
- Tin (Sn)
- Lead (Pb)
- Flerovium (FI)
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