Aluminum forms metallic bonds. Metallic bonds are formed when atoms share a pool of electrons known as the "electron sea." This sea of electrons is what gives metals their characteristic properties such as luster, malleability, ductility, and thermal conductivity. In aluminum, each atom contributes three valence electrons to the electron sea, which are then shared by all the atoms in the metal lattice. This results in a strong bond between the atoms, which is why aluminum is known for its strength and durability.