What happens during the formation of covalent bonds?

During the formation of covalent bonds, atoms share electrons to achieve a full outer electron shell, which contributes to their stability. This sharing allows each atom involved to attain the electron configuration of a noble gas, thereby fulfilling the octet rule for most elements. This process typically occurs between nonmetal atoms, where their electronegativity values are similar, leading to an even distribution of the shared electrons in the bond.

In contrast, the other choices involve different types of bonding or interactions. Transferring electrons, as stated in the first option, is characteristic of ionic bonding rather than covalent bonding. The third option suggests that atoms completely lose their outer shells, which is not how covalent bonds function since the outer shell electrons remain associated with the atoms in a shared state. Lastly, the presence of ionic bonds refers specifically to compounds formed when one atom completely transfers electrons to another, resulting in charged ions that attract each other. Therefore, option B accurately reflects the nature of covalent bonding through the sharing of electrons, which is the key characteristic distinguishing it from other types of chemical bonding.