P-Block Element and Their Compound – I: General Characteristics of Elements of Group 13 (For CBSE, ICSE, IAS, NET, NRA 2022)

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General Characteristics of Elements of Group 13

  • Group consists of .
  • These elements exhibit a group valency of three, but because of the very large input of energy that is necessary to form the 3-valent ions (the sum of three ionization enthalpy) their compound when anhydrous are either covalent or contain an appreciable amount of covalent character.
  • Boron is non-metallic, Aluminum is metallic, and Gallium, indium and thallium are weakly metallic.

Physical Characteristics of Group 13 Element

Physical Characteristics of Group 13 Element

Occurrence and Abundance

  • Boron is a fairly rare element but known because it occurs as concentrated deposits of borax and kernite .
  • Aluminum is the most abundant metal, and the third most abundant element) by weight in the earth՚s crust (Table) .
  • The most important ore of aluminum is bauxite. It is well known and is commercially important.
  • Gallium is twice as abundant as boron, but indium and thallium are much less common.

Abundance of the Element in the Earth՚s Crust by Weight

Abundance of the Element

Boron

Boron can be obtained as an amorphous brown powder by treating borax with hydrochloric acid , igniting the boric acid, obtained, to give oxide and finally reducing the latter with magnesium at a high temperature:

A crystalline form of boron can be obtained by thermal decomposition of boron tri-iodide on a tantalum filament:

It is used in the construction of high impact-resistant steel and in reactor rods for controlling atomic reactions.

Properties of Boron

Amorphous boron is a very reactive element combining directly with oxygen, Sulphur, nitrogen and the halogens to give an oxide, Sulphide, nitride and a halide, respectively.

Reaction of Boron

Some reaction of amorphous boron:

At high temperature

At 1200°C

At very high temperature

At high temperature

when fused with alkali At very high temperature Many metals form borides often (not group I) nonstoichiometric.

Reaction of Aluminum

Reaction with Water and Air

  • Aluminum react with cold water forming and liberating hydrogen.
  • Aluminum react with air forming a very thin oxide film on the surface which protects the metal from further attack.
  • Aluminum burns in nitrogen at high temperatures, forming .

Reaction with Acids and Alkali

Aluminum dissolves in dilute mineral acids liberating hydrogen.

  • Concentrated renders the metal passive because it is an oxidising agent and produces a protective layer of oxide on the surface.
  • Aluminum dissolves in aqueous liberating hydrogen and forming aluminates.

Use of Aluminum

  • Used as structural metals in aircraft, ships, cars, and heat exchangers.
  • In buildings (doors, windows, cladding panels and mobile homes) .
  • Container such as cans for drinks, tubes for toothpaste etc. and metal foil.
  • For cooking utensils.
  • To make electric power cables.

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