For which element would XH3 be a stable species?

The species XH3 refers to a molecule where X is an element and H stands for hydrogen. This type of molecular structure often forms when the element has a specific capability of forming stable bonds with hydrogen in a way that allows the resulting compound to exist under normal conditions.

Phosphorus, represented as P, can form stable compounds with hydrogen known as phosphines (PH3). In this compound, phosphorus has five valence electrons and can utilize these to bond with three hydrogen atoms, allowing the molecule to achieve a stable electronic configuration. Phosphine is known to be a gas at room temperature and exhibits characteristics consistent with stability in appropriate conditions.

While nitrogen can also form ammonia (NH3), the question specifically asks about the XH3 structure, which pertains to elements in the same group in the periodic table, particularly within the context of stability with hydrogen.

Slightly heavier elements like arsenic can form stable hydrides too, but phosphorus is often recognized as the classic example of a stable XH3 species due to its notable chemical properties and the stability of its compounds. The heavier group elements may not display the same level of stability and can sometimes exhibit different bonding characteristics or reactivity compared to phosphorus.

In this light, phosphorus is