Question

why do not the metal ions repel each other in a metallic bond? though the magnitude of negetive charge is less than that of the positive once?

Answer 1

A metal is composed of neutral atoms of the elements that make up the metal, *not* cations of those elements. Neutral atoms have no net charge, so as long as the atoms are not close enough to "feel" the charge separation between the positively charged nucleus, and the negatively charged electron cloud surrounding the nucleus, neutral atoms will not repel one another.

More accurately, in a metal, a fraction of the electrons are "shared" among all the atoms in the metal. This is commonly referred to as a "sea" of electrons. On average, however, each atomic nucleus "owns" enough electrons to maintain charge neutrality (i.e., as enough electrons around the nucleus to cancel the positive nuclear charge), so there is no Coulombic repulsion.