Question

How do you describe the basis of the band theory of metallic bonding?

Answer 1

Hint : To describe the basis of the band theory of metallic bonding, we should go through the whole concept of the metallic bonding and why metallic bonding exists in the metals. We will also discuss more about it.

Complete Step By Step Answer:
Metals have their valence band filled, and due to the absence of a band gap, their conduction band partially filled. The theory predicts that metals will conduct (both heat and) electricity very well and so is generally accepted.
We know that molecular orbitals are formed by overlapping of atomic orbitals. This model uses the molecular orbital approach.
For example the two molecular hydrogen molecules $\left( {{H_2}} \right)$ are formed by overlapping two hydrogen atoms. The energy of the two orbitals is different. One orbital will have higher energy and the other orbital will have lower energy. The energies of the orbitals were represented by the energy level whose magnitude varied with the nuclear distance between the two atoms.
The difference between the energy of two molecular orbital at equilibrium internuclear distance is given as AB.
In general we can say that if n number of atomic orbitals overlaps then they will form n molecular orbitals. The necessary condition for overlapping is that the atomic orbitals should have the same symmetry and should associate with the same or similar amount of energy.

Note :
Metallic bonds occur among metal atoms. Whereas ionic bonds join metals to non-metals, metallic bonding joins a bulk of metal atoms. Bulk properties of metals. Metallic bonding is the attraction between the positive ions in a regular lattice and the delocalised electrons. Delocalised electrons are free to move throughout the whole structure.