What type of bond involves the sharing of electron pairs between atoms?

Covalent bonds involve the sharing of electron pairs between atoms, which allows each atom to attain a full valence shell, achieving greater stability. This type of bond typically forms between nonmetals with similar electronegativities, as they attract the shared electrons equally, resulting in a strong bond. The sharing can be equal (nonpolar covalent bond) or unequal (polar covalent bond), depending on the differences in electronegativity between the atoms involved. This fundamental aspect of covalent bonding is crucial for the formation of many biological molecules, such as proteins and nucleic acids, highlighting its importance in chemistry and life sciences.

In contrast, ionic bonds involve the transfer of electrons from one atom to another, creating ions that attract each other due to opposite charges. Metallic bonds are characterized by a 'sea of electrons' shared among a lattice of metal atoms, facilitating electrical conductivity and malleability. Hydrogen bonds, while they result from attractive forces between polar molecules, do not involve shared electron pairs in the manner characteristic of covalent bonding. This clarification helps to distinguish the unique properties and formation criteria of each bond type.