Why do metals generally form positive ions (cations), while non-metals generally form negative ions (anions)?

Metals typically have 1, 2, or 3 electrons in their outermost shell. They tend to lose these valence electrons to achieve a stable noble gas configuration, forming positively charged ions (cations). Non-metals, on the other hand, usually have 4 to 7 electrons in their outermost shell. They tend to gain electrons to complete their octet and achieve a stable noble gas configuration, forming negatively charged ions (anions).