In which type of bond are valence electrons shared?

In a covalent bond, valence electrons are shared between atoms. This sharing occurs because atoms seek to achieve a more stable electronic configuration, often resembling that of noble gases. By sharing electrons, the participating atoms can fill their outer electron shells, which leads to increased stability for the molecules formed. This is particularly common among nonmetals, where atoms have similar electronegativities, making the equal sharing of electrons favorable.

For instance, in a water molecule (H2O), each hydrogen atom shares one electron with the oxygen atom, resulting in a stable structure where the oxygen has a complete outer shell due to the additional shared electrons from the two hydrogen atoms. Thus, the nature of the covalent bond is characterized by the shared electrons, distinguishing it clearly from the other types of bonds mentioned.