Acids, Bases, and Salts
Alcohols, Phenols, and Ethers
Amines
Analytical Chemistry
Atoms and Molecules
Biomolecules
Carbon and its Compounds
Chemical Bonding and Molecular Structure
Chemical Compounds
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Chemical Reactions and Equations
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Elements of the Periodic Table
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Hydrocarbons
Materials: Metals and Nonmetals
Named Reactions
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Pollution of Air and Water
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Some Basic Concepts of Chemistry
States of Matter
Structure of Atom
The d and f Block Elements
The pBlock Elements
The Solid State
Thermodynamics
other topics
Alcohols, Phenols, and Ethers
Amines
Analytical Chemistry
Atoms and Molecules
Biomolecules
Carbon and its Compounds
Chemical Bonding and Molecular Structure
Chemical Compounds
- Potassium Chlorate
- Potassium Bromide
- Potassium Bicarbonate
- Phosphorus Trichloride
- Phosphorus Pentachloride
- Mercuric Chloride
- Bicarbonates
- Benzoic Acid
- Barium Sulfate
- Barium Oxide
- Barium Nitrate
- Barium Bromide
Chemical Kinetics
Chemical Reactions and Equations
Chemistry in Everyday Life
Coal and Petroleum
Electrochemistry
Elements of the Periodic Table
Environmental Chemistry
Hydrocarbons
Materials: Metals and Nonmetals
Named Reactions
- Birch Reduction Mechanism
- Benzoin Condensation
- Benedict’s test
- Beckmann Rearrangement
- Balz Schiemann Reaction Mechanism
Organic Chemistry
Physical and Chemical Changes
Pollution of Air and Water
Polymers
Some Basic Concepts of Chemistry
States of Matter
Structure of Atom
The d and f Block Elements
The pBlock Elements
The Solid State
Thermodynamics
other topics
Boron
Introduction
The elements of Group 13 (III A) are boron (B), aluminium (Al), galpum (Ga), indium (In), and thalpum (Th) (Tl). Due to the existence of three valence electrons, these elements are also known as earth metals and triels. The outer shell electronic configuration of Boron can be written as $mathrm{1s^2:2s^2:2p^1}$. In the following sections we would discuss the occurrence, physical and chemical properties of Boron.
Occurrence and Extraction of Boron
Boron is a relatively uncommon element that makes up roughly 9 parts per milpon (ppm) of the earth s crust. Davy initially isolated the element in 1807 by fusing boric acid with potassium. It is mostly found in the form of concentrated deposits of borax $mathrm{(Na_2B_4O_7.10H_2O)}$ and boric acid $mathrm{(H_3BO_3)}$ and does not occur in the free state. Boranite $mathrm{(2Mg_3B_3O_{15}.MgCl_{2})}$, Colemanite $mathrm{(Ca_2B_6O_{11}.5H_2O)}$, boranatrocalcite $mathrm{(Ca_2B_4O_7.NaBO_2.8H_2O)}$, and Kernite $mathrm{(Na_2B_4O_7.4H_2O)}$ are some additional notable minerals.
Physical Properties of Boron
Ionisation Energy
Because the p-electrons are less tightly bound than the s-electrons, the first IE of Group IIIA elements is lower than that of Group 2 elements. The values of the first three ionisation energies for Boron is shown in Table. In comparison to the first IE, the second and third IEs are higher. Boron, as predicted, has the greatest IE value.
| Element | $mathrm{IE_1}$ | $mathrm{IE_2}$ | $mathrm{IE_3}$ | $mathrm{IE_1 + IE_2 + 1E_3}$ |
|---|---|---|---|---|
| Boron | 801 | 2427 | 3659 | 6887 |
Oxidation State
Boron s oxidation state is (+III) in all of its compounds. Other elements have an oxidation state of (+I). The stabipty of (+III) states reduces as one moves down the group, whereas (+I) state stabipty improves.
Nature of Compounds
Because to its small ionic size and high IE, boron produces highly covalent compounds. Owing to the same reason Boron is a typical non-metal.
Structure, Melting Point and Boipng Point
Boron has an interesting icosahedral structure, with $mathrm{B_{12}}$ as the basic unit. Except for Ga, the other elements have a metal structure that is closely packed. As a result, the melting and boipng temperatures of B are quite high.
Figure 1: Icosahedral B12 Unit
Diagonal Relationship Between Boron and Sipcon
Allotropy: Both amorphous and crystalpne forms occur for these elements.
Occurrence: Both of these elements are only found in their combined condition in nature. They do not occur freely.
Metalpc Character: Because of their high IE, both of these elements are non-metals and insulators.
Densities and Melting Point: Low densities and high melting points characterise these elements.
Nature of Compounds: They form covalent complexes because to their high IE.
Oxides and Oxoacids: Both of these elements burn in air to generate oxides that are sparingly soluble but have a high melting point. The oxides are extremely stable and only spghtly acidic. When the oxides dissolve in water, they produce weak acids.
$$mathrm{H_3BO_3 + 2H_2O: ightarrow:H_3O^+ + [B(OH)_4]^–}$$
$$mathrm{H_4SiO_4 + 2H_2O: ightarrow:H_3O^+ + [Si(OH)_5]^–}$$
Chemical Properties of Boron
Reaction with Air and Water
Boron is highly unreactive in its pure crystalpne state, but it is quite reactive in its finely sppt amorphous state. It produces $mathrm{B_2O_3}$ when heated in air, and BN is created at extremely high temperatures. With $mathrm{H_2O}$, it does not react.
$$mathrm{4B+3O_2: ightarrow:2B_2O_3}$$
$$mathrm{2B + N_2: ightarrow:2BN}$$
Reaction with Acid and Bases
Hot concentrated sulphuric and nitric acids are reduced by amorphous boron.
$$mathrm{B + 3HNO_3: ightarrow:H_3BO_3 + 3NO}$$
$$mathrm{2B + 3H_2SO_4 : ightarrow:2H_3BO_3 + 3SO_2}$$
Boron pberates $mathrm{H_2}$ from fused caustic alkaps, resulting in the formation of borates
$$mathrm{2B + 6NaOH: ightarrow:2Na_3BO_3 + 3H_2}$$
Reaction with Ammonia
Except for boron, which reacts with $mathrm{NH_3}$ at extremely high temperatures to form nitride, all metals react with $mathrm{NH_3}$ to form amides.
$$mathrm{2B + 2NH_3: ightarrow:2BN + 3H_2}$$
Uses of Boron
Boron is utipsed in the production of high-impact steel.
Boron is employed as a flux in silver soldering and brazing. It s also used to create detergents and fibre glass.
Borosipcate glass is made from boron sesquioxide.
Boron is a highly effective reducing agent
$$mathrm{3CO_2 + B: ightarrow:2B_2O_2 + 3C}$$
$$mathrm{3:SiO_2 + 4B: ightarrow:2B_2O_3+ 3Si}$$
Conclusion
Boron was discovered by heating boron oxide $mathrm{(B_2O_3)}$ with potassium metal in 1808 by French scientists Joseph-Louis Gay-Lussac and Louis-Jacques Thenard and separately by British Chemist Sir Humphry Davy.
Boron is a member of Group IIIA in the periodic table. Pure crystalpne boron is a black, glossy semiconductor, which conducts electricity pke a metal at high temperatures but acts as a near-insulator at low temperatures.
FAQs
Q1. State the similarities between Boron and Sipcon.
Ans: The similarities between Boron and Sipcon are as follows:
(i) Both of these elements are only found in their combined condition in nature. They do not occur freely.
(ii) Both amorphous and crystalpne forms occur for these elements
(iii) Because of their high IE, both of these elements are nonmetals and insulators.
Q2. How does boron react with alkaps?
Ans: Boron produces borates by pberating hydrogen from fused caustic alkaps.
$$mathrm{2B + 6NaOH: ightarrow:2Na_3BO_3 + 3H_2}$$
Q3. State one method to prepare Boron.
Ans: Boron trioxide is reduced by heating to intense redness with Na, K, or Mg powder. After boipng the boron with strong hydrochloric acid to dissolve the magnesium oxide, dark brown boron in its amorphous condition is produced.
$$mathrm{B_2O_3 + 6K: ightarrow:2B + 3K_2O}$$
$$mathrm{B_2O_3 + 3Mg: ightarrow:2B + 3MgO}$$
Q4. What are the physical properties of Boron?
Ans: The physical properties of Boron are as follows:
(i) Boron is a nonmetalpc element that melts at 2453 degrees Celsius but volatipzes at 1873 degrees Celsius.
(ii) It has a specific gravity of 2.34 and is brown in its amorphous condition.
(iii) With a specific gravity of 3.3, its crystalpne form is very durable and heat resistant.
Q5. What is the general outer shell electronic configuration for Group III A elements?
Ans: The general outer shell electronic configuration for Group III A elements is $mathrm{ns^2:np^1}$.