A group 15 element forms dπ-dπ$d\pi-d\pi$ bond with transition metals. It also forms hydride, which is a strongest base among the hydrides of other group members that form dπ-dπ$d\pi-d\pi$ bond. The atomic number of the element is ______.

Related Formula

Basic strength order among Group 15 hydrides drops down the group due to an increase in size and a decrease in charge density:

Core Logic

Let's analyze the properties specified:

• The element must be able to form dπ-dπ$d\pi-d\pi$ bonds with transition metals. Nitrogen cannot form these bonds because it lacks vacant d$d$-orbitals in its valence shell. Therefore, nitrogen is excluded.
• Among the remaining elements (Phosphorus, Arsenic, Antimony, Bismuth) that contain available d$d$-orbitals, basic strength decreases down the group. Phosphorus forms phosphine (PH₃$PH_3$), which is the strongest base among the remaining members.

Step 1: Identify the Atomic Number

The identified element is Phosphorus (P$P$).

The atomic number of Phosphorus is 15$15$.

Pattern Recognition

Pay attention to qualifying statements like 'among elements that form dπ-dπ$d\pi-d\pi$ bonds'. This explicitly excludes second-period elements (like Nitrogen), making Phosphorus (Z=15$Z=15$) the top choice for basicity.

Chapter Mix

Class 12 Chemistry: p-Block Elements