Physical Properties of Group 13 Elements

We know that the periodic table has 18 groups and seven periods, and each group has some physical and chemical properties. Physical properties are not concerned with the chemical composition or change in the chemical composition of an element. However, physical properties deal with other characteristics such as density, colour, hardness, melting point and boiling point, brittleness, lustre, solubility, viscosity, electrical conductivity, etc. Group 13 consists of six elements, with the first element being Boron (B). The others are Aluminium (Al), Gallium (Ga), Indium (In), Thallium (Tl), and Nihonium (Nh). The groups of the periodic table are according to the number of valence electrons in their elements. All the elements of group 13 have three valence electrons in their last shell, that is, the valence shell. Let’s study the physical properties of group 13 elements in detail.

Physical Properties of Group 13 Elements

The occurrence, examples, and physical properties of group 13 elements are listed below:

Occurrence of Elements of Group 13:

• Boron: It is not a naturally-occurring element and is present in nature combined with oxygen and other natural elements. It forms different compounds with other elements in nature such as borates or orthoboric acids. These borates are extensively present in the oceans, sedimentary rocks, and also in soils.
• Aluminium: Aluminium is not present in the free state on earth. However, it is the earth’s most abundant metal, present in different ores such as bauxite and cryolite. Bauxite is the primary ore of aluminium. On processing, it creates alumina. This alumina after refining creates aluminium.
• Gallium: Gallium is a less abundant mineral and is only present in trace amounts in the minerals diaspore, bauxite, sphalerite, germanite, and coal. It is also obtained as a by-product of zinc refining.
• Indium: Like gallium, Indium is also a rare element and is only present in around 0.1 parts per million on earth. It is mostly present with the ores of zinc. Therefore, it is extracted from residues during zinc processing.
• Thallium: We can obtain thallium from the ores of zinc, lead, or copper. It is also present in ore pyrites, which is useful in the production of sulphuric acid. It is usually obtained as a by-product of copper, zinc, and lead refining.
• Nihonium (Nh): It is a synthetic element, that is, it does not occur in nature but is present in laboratories. 

Atomic Radius

On moving down the group, the atomic radius increases due to the addition of one shell. However, in group 13 elements, the atomic radius of Ga is less than Al. This anonymous change in atomic radii is due to the presence of d-orbitals. These d-orbitals are highly diffused and offer a poor shielding effect. As a result, the nuclear charge increases, and the radius decreases. Boron has the smallest atomic radius among the group 13 elements. 

Oxidation States

The group 13 elements have +3 and +1 oxidation states. However, on moving down the group, the stability of oxidation state +1 increases. The increase in the oxidation state is due to the inert pair effect that causes the poor shielding effect of intervening d and f orbitals. The increase in nuclear charges tightly holds the ns electrons that restrict their participation in bonding.

Melting Point

Among the group 13 elements, Boron has the highest boiling point, whereas gallium has the lowest. Gallium, with the lowest melting point, usually exists as a liquid in summers. Boron has a smaller size, forming strong covalent bonds with other atoms. As a result, the atoms are closely packed in the solid-state. Therefore, the melting and boiling points of boron are highest among all other group 13 elements.

Metallic Properties

Boron is a non-metallic strong black-coloured solid. The other elements–gallium, indium, thallium–are soft metals. 

Acidity and Basicity

Boron forms acidic oxides, while aluminium is amphoteric, that is, reacting both as a base and an acid. On moving down the group, the acidic nature of hydroxides of group 13 elements reduces. Boric acid is a weak acid, formed in two-step reactions.

B2O3(s) + 3H2O (l) →2B(OH)3(aq)

B(OH)3(aq)+2H2O(l)→ H3O+(aq)+B(OH) – 4(aq)

Conclusion

Group 13 of the periodic table is commonly called the Boron family, as it contains boron as the first member. There are three valence electrons in this family due to which it is placed in group 13 of the periodic table. The physical properties represent the physical appearance, texture, and electrical conductivity of the elements. Whereas, the chemical properties refer to the change or reactions concerning the chemical composition of the elements. The physical properties deal with density, colour, hardness, melting point and boiling point, brittleness, lustre, solubility, viscosity, electrical conductivity, etc., of the elements. In group 13 elements, the atomic radius of Ga is less than Al. This is due to the poor shielding effect and increased nuclear charge. The group 13 elements have +3 and +1 oxidation states. However, on moving down the group, the stability of oxidation state +1 increases.