What type of bond is formed when two atoms share electrons?

When two atoms share electrons, they form a covalent bond. This type of bond typically occurs between nonmetal atoms, which have similar electronegativities. By sharing electrons, these atoms can achieve a full outer shell of electrons, resulting in greater stability.

The shared electrons allow both atoms to gain the electronic configuration of noble gases, which is energetically favorable. For instance, in a water molecule (H2O), the oxygen atom shares electrons with hydrogen atoms, creating covalent bonds that hold the molecule together.

Covalent bonding can also lead to the formation of molecules with specific shapes and properties, which are essential for the structure and function of biological molecules, including proteins and nucleic acids. This is particularly significant in the context of biology, as it underpins the interactions and reactions that sustain life.

In contrast, other bond types, such as metallic and ionic bonds, operate under different principles where electrons are either delocalized among a lattice of metal atoms (metallic) or transferred from one atom to another, resulting in charged ions (ionic). Valence, on the other hand, refers to the capacity of an atom to bond, rather than a specific type of bond itself.