The element that distinguishes nucleic acids from other macromolecules is phosphorus (P).

Here's why:

* Nucleic acids (DNA and RNA) are made up of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base. The phosphate group contains phosphorus.

* Other macromolecules, like carbohydrates, lipids, and proteins, do not have phosphate groups as a fundamental component of their structure.

Therefore, the presence of phosphorus is a key feature that sets nucleic acids apart from the other major macromolecules.