Name: p-block Elements
Uploaded: 2019-07-19
Duration: 2 min 38 s
Description: Do you know why some elements of the periodic table are known as p-block elements? Learn about p-block elements and their general properties in this video.

Question

Compare and contrast the chemistry of boron and aluminium.

Accepted Answer

The similarities are as follows:

$1 .$ Both have the same valence shell electronic configuration, that is ${ns}^{2} {np}^{1}$ .

$2 .$ Both dissolve in alkalis and evolve hydrogen gas.

$2 B + 6 NaOH \to 2 {Na}_{3} {BO}_{3} + 3 H_{2} 2 Al + 2 NaOH + 2 H_{2} O \to 2 {NaAlO}_{2} + 3 H_{2}$

$3 .$ Both show a common oxidation state of $+ 3$ in the majority of their compounds.

$4 .$ Both react with concentrated $H_{2} {SO}_{4}$ and evolve ${SO}_{2}$ gas.

$2 B + 3 H_{2} {SO}_{4} \to 2 H_{3} {BO}_{3} + 3 {SO}_{2} 2 Al + 6 H_{2} {SO}_{4} \to {Al}_{2} {({SO}_{4})}_{3} + 3 {SO}_{2} + 6 H_{2} O$

$5 .$ Both form oxides of the type $M_{2} O_{3}$ when heated in an atmosphere of oxygen at a high temperature and their oxides are amphoteric in nature.

$6 .$ Both form trichlorides, either by passing chlorine over heated $B$ or $Al$ , or by passing chlorine over a heated mixture of their oxides and charcoal.

$7 .$ Their halides behave as Lewis acids whenever electron donor molecules are available.

$8 .$ Both form nitrides of the type $MN$ when heated in an atmosphere of nitrogen.

$9 .$ Both form sulphides of the type $M_{2} S_{3}$ when heated with sulphur.

$10 .$ Both form similar types of alkyl compounds like $B {({CH}_{3})}_{3}, Al {({CH}_{3})}_{3},$ etc.

The following are the point of differences:

$1 .$ Boron is a non-metal and aluminium is a metal.

$2 .$ Boron is a non-conductor of electricity, while aluminium is a very good conductor of electricity.

$3 .$ The melting point of boron is much greater than aluminium.

$4 .$ Boron shows allotropy. Allotropes are the amorphous and crystalline structures. On the other hand, aluminium is a delicate metal. It does not show allotropy.

$5 .$ Boron forms only covalent compounds, while aluminium can form both covalent and ionic compounds.

$6 .$ Trihalides of boron $({BX}_{3})$ are monomers. On the other hand, aluminium halides exist as dimers $({Al}_{2} X_{6})$ .

$7 .$ Oxides and hydroxides of boron are acidic in nature, while the oxides and hydroxides of aluminium are amphoteric in nature.

$8 .$ Boron forms a number of stable hydrides, while hydrides of aluminium are not stable.

Compare and contrast the chemistry of boron and aluminium.

Important Questions on The Group 13 Elements

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