What is a covalent bond characterized by?

A covalent bond is characterized by the sharing of electrons between two atoms. In contrast to ionic bonds, where electrons are transferred from one atom to another resulting in the formation of charged ions, covalent bonding involves two nonmetals that come together to achieve a full outer electron shell. Each atom contributes at least one electron to the bond, allowing both atoms to attain greater stability through this electron-sharing process.

This phenomenon is fundamental to the formation of many molecules, such as water (H2O) and carbon dioxide (CO2), where shared pairs of electrons enable the constituent atoms to maintain their structural integrity and chemical properties. This type of bonding is key in organic chemistry as well, where covalent bonds form the backbone of complex molecules essential for life.

In terms of the other choices, the transfer of electrons describes ionic bonding rather than covalent bonding. The attraction of oppositely charged ions relates specifically to ionic interactions, and the formation of a metal hydroxide involves specific chemical reactions rather than defining a covalent bond itself. Thus, the act of sharing electrons is what distinctly classifies a covalent bond.