Final answer:
Ionic bonding occurs when atoms gain or lose electrons to form positively-charged cations and negatively-charged anions. The opposite charges of cations and anions attract each other to form an ionic bond.
Step-by-step explanation:
Ionic bonding occurs when atoms, either metals or non-metals, gain or lose electrons. Atoms that lose electrons become positively charged cations, while atoms that gain electrons become negatively charged anions. The opposite charges of cations and anions attract each other, forming an ionic bond. This bond is based on the principle of electrostatics, where opposite charges attract and like charges repel. For example, sodium donates an electron to chlorine to form the cation Na+ and the anion Cl-, and their opposing charges cause them to strongly attract each other.