Why does sodium conduct heat and electricity well?

Sodium conducts heat and electricity well due to the nature of metallic bonding. In its solid state, sodium atoms are held together by a structure where valence electrons are not bound to any specific atom.12

Instead, these valence electrons are nonlocalized, forming a "cloud" of electrons that are free to move throughout the entire crystal lattice. This high degree of electron mobility is the primary factor responsible for the element's ability to conduct both electricity and heat efficiently. When an electrical field is applied, these mobile electrons are free to move, facilitating the flow of current.123