The 13th group elements remarks about their general chemical properties and reactivity

3 The 13th group elements remarks about their general chemical properties and reactivity 

Because the number of orbitals available for boron is higher than electrons (three electrons, four orbitals) boron is an electron-pair acceptor, a Lewis acid and it is prone to form multi-centre bonds. Boron is inert under normal conditions except for attack by fluorine. 

At high temperatures it reacts with most non-metals and most metals. The general chemical inertness of boron at lower temperatures is highlighted by the fact that it resists attack by boiling concentrated aqueous NaOH or by fused NaOH up to 500°C. 

In and T1 differ sharply from boron. They have greater chemical reactivity at lower temperatures, well-defined cationic chemistry in aqueous solutions they do not form numerous volatile hydrides and cluster compounds as boron. Aluminium readily oxidizes in air, but bulk samples of the metal form a coherent protective oxide film preventing appreciable reaction aluminium dissolves in dilute mineral acids, but it is passivated by concentrated HN03. It reacts with aqueous NaOH, while gallium, indium and thallium dissolve in most acids. 

Thallium may be described as a relativistic alkali metal the downshift in energy of the 65 orbital, due to a combination of relativity and shell structure effect, favours the oxidation state I over III (see 4.2.22). The stability of the oxidation state +1 

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