The octet rule is a chemical principle that states:
Atoms tend to gain, lose, or share electrons in order to have eight electrons in their outermost shell, which makes them stable like the noble gases.
- Atoms of metals usually lose electrons to form positively charged ions (cations) with eight electrons in the next inner shell.
- Atoms of non-metals usually gain or share electrons to complete their outer shell and form negatively charged ions (anions) or covalent bonds.
For example, sodium loses one electron to achieve an octet, while chlorine gains one electron to complete its octet. When combined, they form sodium chloride (common salt), a stable compound.