How do the outer electrons of Group 15 elements allow them to form three covalent bonds?

Group 15 elements, also known as the nitrogen group, possess an outermost shell containing five electrons. These electrons are arranged with two in a filled outer s orbital and one in each of the three outer p orbitals.1

The presence of these three half-filled p orbitals is the key to their bonding behavior: they allow the atoms to form three covalent bonds by interacting with the half-filled orbitals of other atoms. This process enables the elements to achieve a stable configuration, often associated with the octet rule, which describes the tendency of atoms to attain an eight-electron outer shell.12

After these three covalent bonds are formed, the two electrons in the s orbital remain as an unshared, or lone, pair. While this lone pair can sometimes act as an electron donor in the formation of complexes, the three half-filled p orbitals remain the primary mechanism for the group's characteristic ability to form three covalent bonds.1