Boron – The Group IIIA Element


Boron is a chemical element with the symbol B and atomic number 5.

Produced completely by cosmic ray spallation and supernovae and not by outstanding nucleosynthesis.

Occurrence of Boron

Boron is not an abundant element. It constitutes about 0.001 percent by weight of Earth’s crust. It happens in traces in a lot of soils and has been found to be essential in extremely small amounts for the proper growth of numerous plants. Boron is always found in nature combined with oxygen, usually as oxyborate ions. Boron present mainly as salts of different polyboric acids.

PeculiarBehaviour of Boron

Boron is the very first member of the Group IIIA, it reveals lots of dissimilarities with the members of its own group. The difference in the properties of boron and those of the other members of the series is generally due to the big distinction in their sizes and ionization energies.

  1. Boron is the only element in GroupIIIA which is non-metallic in behavior
  2. It is the only element with less than 4 electrons in the outermost shell which is not a metal.
  3. Boron always utilizes all three of its valence electrons for bonding purposes and its common oxidation states are + 3 and -3.
  4. Among the outstanding functions of the chemistry of boron is its ability to form molecular addition substances.
  5. Boron does not form ionic substances with sulphate, nitrate, or other anions because boron does not form a stable cation.
Compounds of Boron

Borax (Sodium Tetraborate Na2B4O7.10H2O)

Borax is the sodium salt of tetra boric acid. It is the most crucial of all borates.


Borax takes place as a natural deposit called tincal in the dried-up lakes of Tibet and California.

  • 1.Formally borax was produced by treating a hot solution of boric acid with the appropriate amount of soda ash.


  • 2.Now-a-days borax is almost exclusively obtained from calcium borate. Carefully powdered colemanite is boiled with Na2CO3 option when CaCO3 precipitates out and a mixture of borax and sodium metaborate is formed.


The clear solution from the top is removed and is then permitted to crystallize when crystals of borax separate out. To get more borax, CO2 is blown through the mother-liquor, the salt metaborate is decomposed into borax, which separates out in the form of fine crystals.


  • 3.Borax might also be acquired from tincal (Na2B4O7.10H2O) by treating tincal with water and subsequently vaporizing the clear solution when crystals of borax separate out.
  1. Borax is a white, crystalline solid. It is moderately soluble in cold water but is more soluble in hot water: 100 grams of water dissolve 3 grams of decahydrate at 10 ° C and 99.3 grams at 100 ° C. If a saturated solution be enabled to crystallize above 62 ° C, octahedral crystals of the pentahydrate, Na2B4O7.5H2Oseparate out, if the temperature is below 62 ° C, the decahydrate is formed. Its liquid solution is alkaline in nature due to hydrolysis.


The hydrolysis is prevented in the existence of glycerine.


  1. When heated up, borax loses water and swells up into a white permeable mass due to the expulsion of water: on more heating, it melts into a clear transparent glass, which liquifies many metallic oxides forming colored beads. This reaction forms the basis of the borax bead test.


  1. Its aqueous solution reacts with HCl or H2SO4 to form boric acid:


  1. When borax is heated with ammonium chloride, boron nitride is produced:


  1. Borax when dissolved in water ionizes as:


Hydrolysis of B4O7-2 happens as follows:


So, a strong alkali (NaOH) is formed which is highly ionized. On the other hand, boric acid (H3BO3) is ionized to some degree, due to the fact that it is a weak acid. Thus, the solution of borax as a whole is alkaline in nature.

  • 6.Borax Bead Test
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Prepare a loop at the end of a platinum wire. Heat the wire and take a little powdered borax on the hot loop. Heat again, borax first inflates and then melts into colorless, glasslike bead on the loop. Now put a couple of grains of the compound, under examination, on the beads and re-heat it first in the oxidizing flame and then in the reducing flame.


Chemistry of the Borax-bead Test

Borax, when fused, is decomposed into sodium metaborate and boric anhydride.


The metallic oxide formed from the compound, under examination, integrates with B2O3giving the colored metallic borates. With cupric oxide, the beads are colored blue in the oxidizing flame because cupric borates are blue in color.


Uses of Borax
  1. It is used to prepare borate glass, which is heat resistant.
  2. It is used in the softening water.
  3. It is utilized in borax bead test, for the detection of metallic cations.
  4. It is used in metallurgical operations.
  5. It is utilized as a flux in welding and in metallurgy.
  6. It is used in making cleaning powders.
  7. It is used in leather industry for tanning and dyeing.
  8. It is used in cosmetics, soaps, fabrics, paints, medicine, match market and as a preservative.
Boric Acids

There are four important boric acids. Out of these orthoboric acid is the most important and stable one. The remaining acids are stable in solid-state and become orthoboric acid in solution:

(i) Orthoboric Acid, H3BO3

(ii) Metaboric Acid, HBO2

(iii) Tetra Boric Acid, H2B4O7

(iv) Pyroboric Acid, H6B4O9


Orthoboric Acid or Boric acid (H3BO3)

It is a white crystalline chemical compound (triclinic), moderately soluble in cold water (2.6% at 40 ° C) but dissolves readily in hot water (37% at 107 ° C). This temperature variation in solubility forms the basis for its separation and filtration.

Preparation of Boric acid on Industrial Scale
  • 1.From Colemanite

On an industrial scale, boric acid is prepared from a natural calcium borate called colemanite (Ca2B6O11. 5H2O) by suspending it in boiling water while Sulphur dioxide is passed through it. Boric acid crystallizes out from the solution while, the other product CaSO3 stays in the solution.


  • 2.From Borax:

A hot concentrated solution of borax is treated with a determined amount of conc. H2SO4. On cooling, crystals of boric acid formed, separate out.


Properties of Boric Acid
  1. Boric acid is a white glossy crystalline solid having a soft soapy touch, very slightly soluble in cold water but fairly soluble in hot.
  2. It is volatile in steam.
  3. It reacts with ethyl alcohol forming ethyl borate.


  1. When heated strongly, it swells to frothy mass losing water particles. It is first converted into metaboric acid, then to tetra boric acid and finally to boric anhydride.



  1. It is a very weak acid and ionizes to a very restricted degree primarily as a monobasic acid.


  1. Its solution has no impact on methyl orange, although it turns blue litmus red.
  2. It is partly neutralized by caustic soda to provide borax.

  1. When boric acid is neutralized by soda ash (Na2CO3), borax is obtained.


  1. Boric acid being a weak acid, cannot be titrated with alkalies in the usual manner. In the existence of glycerol, however, it can be titrated against a basic alkali using phenolphthalein as an indicator.
Uses of Boric Acid
  1. Boric acid is utilized in medicines as an antiseptic, e.g. cleaning powder, boric lotion, and the boric solution is used as an eye-wash.
  2. It is used in pottery as a glaze because borate glazes are more fusible than silicate glazes and have a higher coefficient of expansion.
  3. It is likewise used in the candle industry for the stiffening of wicks.

Multiple Choice Questions (MCQs) with Answers

  1. What is the atomic number of Boron?
    • A) 3
    • B) 5
    • C) 7
    • D) 9
    • Answer: B
  2. How is Boron primarily produced in nature?
    • A) Fusion reactions
    • B) Stellar nucleosynthesis
    • C) Outstanding nucleosynthesis
    • D) Cosmic ray spallation and supernovae
    • Answer: D
  3. What percentage does Boron constitute by weight in Earth’s crust?
    • A) 0.0001%
    • B) 0.001%
    • C) 0.01%
    • D) 0.1%
    • Answer: B
  4. Why does Boron exhibit dissimilarities with other Group IIIA elements?
    • A) Difference in size and ionization energies
    • B) Similarities in size and ionization energies
    • C) Similar chemical properties
    • D) Identical electronic configurations
    • Answer: A
  5. What is the common oxidation state of Boron?
    • A) +1
    • B) +2
    • C) +3
    • D) +4
    • Answer: C
  6. Which acid is the most stable among the boric acids?
    • A) Metaboric Acid
    • B) Tetra Boric Acid
    • C) Pyroboric Acid
    • D) Orthoboric Acid
    • Answer: D
  7. From which natural deposit is Borax obtained?
    • A) Amazon rainforest
    • B) Dried-up lakes of Tibet and California
    • C) Arctic glaciers
    • D) Volcanic eruptions
    • Answer: B
  8. How is Borax manufactured on an industrial scale from colemanite?
    • A) Treatment with hot water
    • B) Boiling with Na2CO3 solution
    • C) Mixing with sulfuric acid
    • D) Heating with ammonium chloride
    • Answer: B
  9. What is the color of borax beads when cupric oxide is added in the oxidizing flame?
    • A) Red
    • B) Green
    • C) Blue
    • D) Yellow
    • Answer: C
  10. What is the primary use of Borax in the pottery industry?
    • A) Metal extraction
    • B) Glaze preparation
    • C) Water softening
    • D) Cleaning powders
    • Answer: B
  11. Which acid is formed when Borax is fused?
    • A) Orthoboric Acid
    • B) Metaboric Acid
    • C) Pyroboric Acid
    • D) Tetra Boric Acid
    • Answer: B
  12. What is the primary use of Boric Acid in medicines?
    • A) Antiseptic
    • B) Glazing agent
    • C) Stiffening of wicks
    • D) Metallurgy
    • Answer: A
  13. What is the solubility of Borax in hot water at 100 °C?
    • A) 50 grams per 100 grams of water
    • B) 75 grams per 100 grams of water
    • C) 99.3 grams per 100 grams of water
    • D) 100 grams per 100 grams of water
    • Answer: C
  14. In which industry is Borax used for water softening?
    • A) Pottery
    • B) Metallurgy
    • C) Medicine
    • D) Candle industry
    • Answer: C
  15. What does Boric acid react with to form ethyl borate?
    • A) Ethanol
    • B) Methanol
    • C) Propanol
    • D) Butanol
    • Answer: A
  16. Which acid is formed when Borax is neutralized by soda ash (Na2CO3)?
    • A) Orthoboric Acid
    • B) Metaboric Acid
    • C) Tetra Boric Acid
    • D) Pyroboric Acid
    • Answer: A
  17. What happens to Borax beads when heated with ammonium chloride in the reducing flame?
    • A) They turn red
    • B) They turn green
    • C) They become colorless
    • D) They turn blue
    • Answer: C
  18. How is Boric acid primarily prepared from colemanite on an industrial scale?
    • A) Treatment with hot water
    • B) Boiling with Na2CO3 solution
    • C) Reacting with sulfur dioxide
    • D) Heating with ammonium chloride
    • Answer: C
  19. What is the primary use of Borax in the candle industry?
    • A) Glazing
    • B) Stiffening wicks
    • C) Water softening
    • D) Metal extraction
    • Answer: B
  20. Which property of Borax makes it suitable for use in the borax bead test?
    • A) Solubility in water
    • B) Melting point
    • C) Formation of glassy beads
    • D) Boiling point
    • Answer: C
  21. What is the predominant oxidation state of Boron in its compounds?
    • A) +1
    • B) +2
    • C) +3
    • D) +4
    • Answer: C
  22. In which industry is Borax commonly used for metallurgical operations?
    • A) Pottery
    • B) Medicine
    • C) Metallurgy
    • D) Candle industry
    • Answer: C
  23. How is Boric acid primarily prepared from borax?
    • A) Boiling with water
    • B) Boiling with Na2CO3 solution
    • C) Treatment with sulfuric acid
    • D) Heating with ammonium chloride
    • Answer: C
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Frequently Asked Questions (FAQs)

  1. What is Boron, and what is its atomic number?
    • Boron is a chemical element with the symbol B and atomic number 5. It is produced by cosmic ray spallation and supernovae.
  2. How abundant is Boron in Earth’s crust?
    • Boron constitutes about 0.001 percent by weight of Earth’s crust.
  3. In what form is Boron found in nature?
    • Boron is found in nature combined with oxygen, usually as oxyborate ions. It mainly exists as salts of different polyboric acids.
  4. What makes Boron unique in Group IIIA?
    • Boron, as the first member of Group IIIA, exhibits dissimilarities with other members. Its non-metallic behavior, fewer electrons in the outermost shell, and common oxidation states of +3 and -3 set it apart.
  5. What are the compounds of Boron, and which is the most crucial borate?
    • Boron forms compounds like Borax (Sodium Tetraborate Na2B4O7.10H2O). Borax is the most crucial borate.
  6. How is Borax manufactured?
    • Borax can be obtained from calcium borate or tincal through specific industrial processes involving boiling with sodium carbonate and crystallization.
  7. What is the significance of the Borax bead test?
    • The Borax bead test is used for the detection of metallic cations. Borax beads form glassy beads when heated, providing valuable information about the compounds under examination.
  8. How is Boric acid prepared on an industrial scale?
    • Boric acid is primarily prepared from colemanite (Ca2B6O11. 5H2O) or borax by treating them with specific reagents like sulfur dioxide or concentrated sulfuric acid.
  9. What are the properties of Boric Acid?
    • Boric acid is a white crystalline solid, moderately soluble in cold water but more soluble in hot water. It is volatile in steam and reacts with ethyl alcohol, forming ethyl borate.
  10. In what industries is Borax commonly used?
    • Borax finds applications in various industries, including metallurgy, ceramics (glazing), candle-making (stiffening wicks), and as a flux in welding.
  11. What are the different boric acids, and which one is most stable?
    • The four important boric acids are Orthoboric Acid, Metaboric Acid, Tetra Boric Acid, and Pyroboric Acid. Orthoboric Acid is the most important and stable one.
  12. What are the uses of Boric Acid?
    • Boric acid is used in medicines as an antiseptic, in pottery glazes, and in the candle industry for stiffening wicks. It also finds applications in cleaning powders, tanning, dyeing, cosmetics, soaps, fabrics, paints, medicine, and as a preservative.
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Q12: Write the names of minerals of boron?

Ans: Borax or Tincal, Colemanite, Orthoboric acid.

Q13: What is the action of an aqueous solution of borax on litmus?

Ans: When borax is dissolved in water, it gives an alkaline solution due to hydrolysis. Since the solution is alkaline in nature it turns red litmus blue.

Q14: How borax removes the hardening of water?

Ans: The hardness is due to soluble salts of calcium and magnesium in water. When borax is treated with hard water, it removes Ca2+ and Mg2+ ions as insoluble calcium and magnesium tetra borate respectively.

Q15: What happens when boric acid is treated with caustic soda?

Ans: Boric acid on treatment with caustic soda (NaOH) gives borax.


The comprehensive tutorial on Boron, the Group IIIA element, explores various facets, from its occurrence to unique behaviors, compounds, the chemistry of the Borax-bead test, and practical applications. Boron, denoted by B with an atomic number of 5, is relatively scarce, comprising about 0.001 percent of Earth’s crust. Its distinct behavior in Group IIIA, non-metallic characteristics, and specific chemistry differentiate it from other elements in the series.

Key Points:

  1. Boron’s Peculiar Behavior:
    • Non-metallic nature in Group IIIA.
    • Utilizes all three valence electrons for bonding.
    • Common oxidation states: +3 and -3.
    • Forms molecular addition substances.
  2. Compounds of Boron:
    • Borax (Sodium Tetraborate Na2B4O7.10H2O).
    • Occurrence in natural deposits like tincal.
    • Manufacturing methods from boric acid or calcium borate.
  3. Chemistry of the Borax-Bead Test:
    • Important technique for detecting metallic cations.
    • Reveals insights into compounds under examination.
  4. Uses of Borax:
    • Preparation of borate glass.
    • Softening water.
    • Metallurgical operations.
    • Flux in welding and metallurgy.
    • Cleaning powders, tanning in the leather industry, cosmetics, and more.
  5. Boric Acids:
    • Four significant types, with Orthoboric Acid (H3BO3) being crucial and stable.
    • Varied industrial applications.
  6. Orthoboric Acid (H3BO3):
    • White crystalline compound, moderately soluble in water.
    • Utilized in numerous applications due to its unique properties.
  7. Preparation of Boric Acid on Industrial Scale:
    • Methods involving Colemanite and Borax, explained in detail.
  8. Properties and Uses of Boric Acid:
    • Physical and chemical properties.
    • Weak acid with applications in medicine, pottery, and the candle industry.