Question

The electronegativity of aluminium is similar to:
A ) Boron
B ) Carbon
C ) Lithium
D ) Beryllium

Answer 1

Hint: Electronegativity is the tendency of an atom, in a molecule, to attract a shared pair of electrons. To relate electronegativity of aluminium we will compare diagonal relationship with aluminium with other elements.

Complete answer:
> In the second and third period of the periodic table, there are certain pairs of diagonally adjacent elements that show diagonal relationship. These pairs of diagonally adjacent elements, shows some similarity in the properties. The extent of these similarities in the properties is much lower than the similarities within a group. These similarities in the properties of diagonally adjacent elements are due to the similar polarizing power, similar ionic charge to size ratio of diagonally adjacent elements.
> Second period metals that are present in groups 1, 2 and 13, show diagonal relationship. Lithium shows diagonal relationship with magnesium. Beryllium shows diagonal relationship with aluminium. Boron shows a diagonal relationship with silicon.
> Aluminium is the diagonally opposite element of beryllium. Beryllium and aluminium have similar atomic sizes. They have a similar charge to size ratio. Hence, Beryllium and aluminium have similar properties as they show diagonal relationship.
> The electronegativity of aluminium is 1.5. The electronegativity of beryllium is 1.5.
> The electronegativity of aluminium is similar to the electronegativity of beryllium.

Hence, the correct option is the option D ) Beryllium.

Additional Information Beryllium and aluminium show a tendency to form covalent compounds. Both beryllium chloride and aluminium chloride are covalent in nature and soluble in organic solvents.
Both beryllium chloride and aluminium chloride are Lewis acids and are Friedel Crafts catalysts.
Both beryllium chloride and aluminium chloride have chlorine bridge structures in the vapour phase. Beryllium and aluminium have similar polarizing power.

Note: Boron and aluminium are present in the same group. Yet they do not have similar electronegativity values. This is because, on moving down the group, the electronegativity decreases.