Final answer:
Metallic bonding is characterized by immobile cations surrounded by a sea of delocalized, mobile electrons, which is responsible for the typical properties of metals.
Step-by-step explanation:
The type of bonding that involves immobile cations surrounded by mobile electrons is known as metallic bonding. In metallic bonds, electrons in the outer energy levels of the metal atoms are not associated with any specific atom and are free to move throughout the structure. This essentially forms a 'sea' of delocalized electrons around the metal cations. These mobile electrons facilitate many of the properties of metals, such as electrical conductivity and malleability.