Group 13 2 Flashcards
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Why is boron unreactive in its crystalline form?
Because its structure makes it chemically inert.
How does aluminium resist corrosion?
It forms a very thin oxide layer that protects it from further attack.
What happens when amorphous boron and aluminium metal are heated in air?
They form B₂O₃ and Al₂O₃, respectively.
What do boron and aluminium form when heated with dinitrogen at high temperatures?
They form nitrides.
How does the nature of oxides change down Group 13?
Boron oxide is acidic, aluminium and gallium oxides are amphoteric, and indium and thallium oxides are basic.
What happens when boron trioxide reacts with metallic oxides?
It forms metal borates.
Does boron react with acids and alkalies at moderate temperatures?
No, boron does not react with acids and alkalies even at moderate temperatures.
How does aluminium behave with acids and alkalies?
Aluminium dissolves in mineral acids and aqueous alkalies, showing amphoteric character.
What happens when aluminium reacts with dilute HCl?
It liberates dihydrogen gas. Equation: 2Al(s) + 6HCl (aq) → 2Al³⁺ (aq) + 6Cl⁻ (aq) + 3H₂ (g)
What happens when aluminium is treated with concentrated nitric acid?
It becomes passive due to the formation of a protective oxide layer.
How does aluminium react with aqueous alkali?
It liberates dihydrogen gas and forms sodium tetrahydroxoaluminate(III). Equation: 2Al (s) + 2NaOH(aq) + 6H₂O(l) → 2Na⁺ [Al(OH)₄]⁻ (aq) + 3H₂(g)
How do Group 13 elements react with halogens?
They form trihalides, except for TlI₃.
What is the general equation for the reaction of Group 13 elements with halogens?
2E(s) + 3X₂(g) → 2EX₃(s) (X = F, Cl, Br, I)
What happens when the trichlorides, bromides, and iodides of Group 13 elements are added to water?
They are hydrolyzed because they are covalent in nature.
What species exist in aqueous medium for Group 13 elements (except boron)?
Tetrahedral [M(OH)₄]⁻ and octahedral [M(H₂O)₆]³⁺.
Why are monomeric trihalides of Group 13 strong Lewis acids?
Because they are electron-deficient.
How does boron trifluoride (BF₃) react with ammonia (NH₃)?
It forms a Lewis acid-base complex to complete boron’s octet. Equation: BF₃ + NH₃ → F₃B - NH₃
Why is boron’s maximum covalence limited to 4?
Because boron lacks d orbitals.
Why can aluminium and other Group 13 elements have a covalence greater than 4?
Because they have available d orbitals.
Why do some metal halides like AlCl₃ form dimers?
They dimerize through halogen bridging (e.g., Al₂Cl₆) to complete the metal’s octet.
Why is boron unable to form the BF₆³⁻ ion?
Due to the non-availability of d orbitals, boron cannot expand its octet beyond four bonds.
What are the physical properties of boron?
Boron is extremely hard, refractory, has a high melting point, low density, and very low electrical conductivity.
Where are boron fibers used?
Boron fibers are used in making bullet-proof vests and light composite materials for aircraft.
Why is boron-10 isotope important in the nuclear industry?
Boron-10 has a high ability to absorb neutrons, so metal borides are used as protective shields and control rods.
What is the main industrial application of borax and boric acid?
They are used in manufacturing heat-resistant glasses like Pyrex, glass wool, and fiberglass.
How is borax used in metalwork?
Borax is used as a flux for soldering metals.
How does borax contribute to earthenware production?
It provides heat, scratch, and stain-resistant glazed coatings to earthenware.
Where is borax used in personal care?
It is a constituent of medicinal soaps.
How is orthoboric acid solution used medically?
It is used as a mild antiseptic.
What are the physical properties of aluminum?
Aluminium is a bright silvery-white metal with high tensile strength.
What are the conductivity properties of aluminum?
Aluminium has high electrical and thermal conductivity.
How does aluminum compare to copper in electrical conductivity?
On a weight-to-weight basis, aluminium’s electrical conductivity is twice that of copper.
Where is aluminum commonly used?
Aluminium is used extensively in industry and everyday life.
What elements does aluminum form alloys with?
Aluminium forms alloys with Cu, Mn, Mg, Si, and Zn.
What shapes can aluminum and its alloys be made into?
They can be shaped into pipes, tubes, rods, wires, plates, or foils.
What industries use aluminum and its alloys?
They are used in packaging, utensil making, construction, aeroplanes, and transportation.
Why is the domestic use of aluminum and its compounds reduced?
Their use is reduced due to their toxic nature.
