Here's why:

* Atoms are electrically neutral: Atoms have an equal number of protons (positively charged) and electrons (negatively charged).

* Sodium's atomic structure: Sodium has 11 protons and 11 electrons. The positive charges from the protons perfectly balance the negative charges from the electrons.

Important note: While a sodium atom itself is neutral, it readily loses one electron to become a sodium ion (Na+), which has a positive charge.