Elements: Group 15

In Group 15 elements, you will find phosphorus, arsenic, antimony, and bismuth elements. While moving along the group, we see a change from nonmetallic to metallic due to a metalloid characteristic. Nitrogen and phosphorus are nonmetals, whereas arsenic and antimony are examples of metalloids, and bismuth is an example of a typical metal.

Group 15 elements are known as the Nitrogen Group, which includes elements such as nitrogen, phosphorus, arsenic, antimony, and bismuth, which is composed of chemical elements. It is also referred to as the Representative Elements since they are positioned on the right-hand side of the group 15 periodic table, close to the p-block element, and are hence considered representative. Nitrogen, phosphorus, arsenic, antimony, and bismuth are all elements that belong to the group 15 periodic table. Phonogenic elements are a class of elements that have been classified, and pnictides are the compounds that have been produced by combining these elements.

The group 15 elements include five elements :

• Nitrogen

• Phosphorus

• Arsenic

• Antimony

• Bismuth

Electronic configuration of Group 15 elements

Elements belonging to group 15 are distinguished by having five electrons in their valence shells, and the usual electrical configuration for group 15 is s2p3ns2n.

Physical properties of Group 15 elements

Allotropy

Only bismuth lacks allotropy in this group. Allotropic nitrogen is found in two forms: nitrogen and nitrogen. Phosphorus is found in many allotropic structures. The allotropic structures of red and white phosphorus are vital.

The most prevalent allotropic arsenic structures in nature are black, grey, and yellow. The yellow colour of antimony is also an allotropic structure. It is also metallic and explosive.

Boiling point

The boiling point of hydrides drops from ammonia to phosphine and then increases from phosphine to bismuth. Their melting points are monitored according to a similar trend.

Electronegativity

The ability of a particle to draw a shared pair of electrons closer to itself is known as electronegativity. Because of the rise in atomic radius as one moves down the group, the electronegativity rapidly decreases.

Metallic Characteristics

Group 15 elements have a lower metallic content. As one moves down the group, from N to Bi, the metallic characteristic becomes increasingly apparent.

Nonmetallic elements like N and P are nonmetallic, partly nonmetallic elements like As and Sb are partially nonmetallic, and metals like Bi are metals.

Chemical properties of Group 15 elements

Reaction to halogens

All group 15 elements also known as Nitrogen Family react with halogens to generate trihalides and pentahalides. They react with the general formulas EX3 and EX5, respectively.

   2E      +       2X2          →          2EX3

Halogen  Trihalide

    2E      +       5X2          →          2EX5

Halogen Pentahalide

Trihalides include NF3, PF3, AsF3, SbF3, and BiF3.

Except for nitrogen, these trihalides are all the same. Phosphorus, arsenic, and antimony produce pentahalides when their valence shells’ unoccupied d orbitals overlap. Nitrogen’s valence shell lacks an occupied d orbital, preventing pentahalide formation. Pentahalides have stronger covalent bonds than trihalides. From nitrogen to bismuth, halides lose their covalent character.

Each element in group 15 interacts with metals to generate binary compounds having a -3 oxidation state. Metals are represented by M, while group 15 elements are represented by E. Calcium phosphide, nitride, etc., are examples.

3M   +    2E        →     M3E2

Binary compound

3Ca  +     N2        →    Ca3N2

Calcium nitride

6Ca  +     P2        →    2Ca3P2

Calcium phosphide

6Zn  +     4Sb       →    2Zn3Sb2

 Zinc antimonide

6Mg  +     4Bi       →    2Mg3Bi2

Magnesium bismuthide

Reactivity towards hydrogen

15th group elements react with hydrogen to generate hydrides of the type EH3. In this case, E can be any element from group 15, such as nitrogen, phosphorus, arsenic, antimony, or bismuth.

2E + 3H2 → 2EH3

Hydrogen Hydride

N2 + 3H2 → 2NH3

Nitrogen Ammonia

P4 + 6H2 → 4PH3

Phosphorus Phosphine

AS4 + 6H2 → 4ASH3

Arsenic Arsine

4Sb + 6H2 → 4SbH3

Antimony Stibine

4Sb + 6H2 → 4SbH3

Bismuth Bismuthine          

Stability

The inertness of hydrides reduces as they progress from ammonia to bismuth. This is because the size of the central atom E rises as the group progresses. The E–H bond becomes noticeably weaker as the size of the core atom increases.

The covering between the orbitals of E and hydrogen will become less effective as the size of the universe grows. This is the cause for the decline in the inertness of hydrides as they move down the group.

Reducing character

Hydrides generated from the 15th group elements are significantly lower. A decrease in the quality and strength of the EH bond as one progresses through the group of hydrides from ammonia to bismuth results in an increase in the reducing character of hydrides. Bismuth is the most powerful reducing agent known to science among any of the hydrides of group 15 elements.

Basic nature

The hydrides of these elements are found in their most basic forms in nature. They function as Lewis bases due to the accessibility of a lone pair of electrons located on the core atom. As we travel along with the group, the fundamental character decreases in proportion to the increasing size of the central atom.

Applications of Group of 15 elements

• Two elements, nitrogen and phosphorus, are required to survive all living things.

• The majority of the Earth’s atmosphere is made up of nitrogen gas, or N2. Pnictides are diatomic pictogen molecules such as this, which may be natural. A covalent triple bond is formed between pnictide atoms due to the valency of the atoms.

• Phosphorus is found in various products, including matches, pyrotechnics, and fertilisers. It is also utilised in the production of phosphoric acid.

• Arsenic is a toxic element. It has been employed as a poison and a rodenticide in many applications.

• Antimony is used in the production of alloys.

• Bismuth is used in pharmaceuticals, paint, and as a catalyst.

Conclusion

In group 15, phosphorus and nitrogen are nonmetals, arsenic and antimony are semimetals, while bismuth is a metal. Nitrogen compounds have nine oxidation states. The inert-pair effect reduces the stability of the +5 oxidation state from phosphorus to bismuth. The lighter pnictogens form compounds in the −3 oxidation states due to their higher electronegativity.