Here's why:

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

* Cations lose electrons: To become positively charged, an atom must lose one or more electrons. This leaves it with more protons than electrons, resulting in a net positive charge.

Example: A sodium atom (Na) can lose one electron to become a sodium cation (Na+), which has a +1 charge.