Each atom has certain electrons orbiting around the nucleus. When atoms are brought together, the electrons shift their energy levels by some amount (Pauli exclusive priciple) and results in formation of band. An electron can lie anywhere in this band. An electron in the conduction band can float around the material contributing to conduction.

But is every electron associated with a particular atom or it can go and start orbiting in any atom. What is floating electron. Does a conducting electron move from atom to atom? or the atom (in which the free electron exists) moves along with electron inside the material?