Here's why:

* Neutral Sodium Atom: A neutral sodium atom has 11 protons (positive charge) and 11 electrons (negative charge), making it electrically neutral.

* Ion Formation: Sodium readily loses one electron to achieve a stable electron configuration.

* Cation: When sodium loses an electron, it has 11 protons and only 10 electrons, resulting in a net positive charge of +1. This positively charged sodium ion is denoted as Na+.