Final answer:
Metallic bonding is a sea of electrons in which metal ions are surrounded by a mobile cloud of valence electrons.
Step-by-step explanation:
Metallic bonding is best described as a sea of electrons. In metallic bonding, metals exist as a collection of positively charged ions arranged in a crystal lattice. The outermost electrons of the metal atoms are free to move throughout the lattice, creating a sea of electrons. This sea of electrons is responsible for the unique properties of metals, such as their ability to conduct electricity and their high melting points.