Question

If ionic bonds form after transfer of electrons and covalent bonds form through sharing of electrons, how do metallic bonds form?

Answer 1

Metallic bonds are rationalized on the basis of a different paradigm.

Explanation:

In a metallic structure, EACH metal atom is conceived to contribute one or more of its valence electrons to the bulk material; if you like the electrons are delocalized to the entire metal lattice. The result? Well, the familiar description is `"positive ions in a sea of electrons"`.

And this picture of metallic bonding rationalizes familiar metallic properties: `"malleability"`, the ability of the metal to be beaten out into a sheet; `"ductility"`, the ability of the metal to be drawn out into a wire; `"thermal and electrical conductivities"`.

With some metals you can demonstrate these properties at room temperature. You can roll out sodium metal as you would roll out pastry (easier than pastry as a matter of fact); you could also put sodium metal into a special die, wind a thread down, and force out sodium wire.

With other metals, malleability and ductility only become apparent at higher temperatures. Significantly these metals, e.g. copper, iron, are metals with SEVERAL valence electrons. They have MORE valence electrons involved in `"metallic bonding"`, and thus their bonding requires more energy to deform.