Which statement about covalent bonds is true?

• A. They involve transfer of electrons to form ions
• B. They involve sharing of electrons between atoms
• C. They involve delocalized electrons in metals
• D. They are formed by ionic attraction between metal cations and nonmetal anions

Answer: (B)

Covalent bonds are formed when two atoms share electrons so both can achieve a more stable electron arrangement, often filling their valence shells. This sharing is the defining feature, making bonds localized between the bonded atoms rather than transferring electrons to create ions. That's why molecules like H2, O2, or H2O are held together by covalent bonds. The shared electrons can be shared equally, producing nonpolar bonds, or unequally, producing polar bonds, depending on how strongly each atom attracts the electrons. Covalent bonding contrasts with metallic bonding, where electrons are delocalized across a lattice, and with ionic bonding, where electrons are transferred and ions are held together by electrostatic attraction.