How do you explain metallic bonding in terms of the sparsely populated outermost orbitals of metal atoms?
A metal consists of a close-packed array of metal atoms that EACH contribute ONE or TWO or THREE (or more) electrons to the lattice. The result? Metallic bonding, which is aptly described as
Alkali, and alkali earth metals with only ONE or TWO electrons to contribute the metallic lattice, tend to be soft, and of low melting point. Metals with many valence electrons to contribute tend to be very high melting, and possess good electrical and thermal conductivity.