Chemical Bonding

Ionic, covalent, and metallic bonds — how atoms connect

Atoms bond because they become more stable when they share, transfer, or pool their valence electrons. Ionic bonds form when one atom transfers electrons to another — typically a metal giving electrons to a nonmetal (e.g., Na donates 1 electron to Cl, forming NaCl). The resulting positive and negative ions attract strongly, creating crystal lattices. Covalent bonds form when two nonmetals share electron pairs (e.g., two oxygen atoms share 2 pairs in O₂). The shared electrons sit between the nuclei, holding them together. Metallic bonds occur in pure metals: atoms release their valence electrons into a shared 'electron sea' that flows freely between positive metal cores. This explains why metals conduct electricity and can bend without breaking. The electronegativity difference between two atoms predicts which bond type forms: above ~1.7 tends toward ionic, below ~1.7 tends toward covalent, and metallic bonding occurs between identical metal atoms.