In the tight binding approximation, atomic orbitals lead to the formation of band- structure when many atoms are brought together. magnesium has an atomic con- figuration of 1s22s22p3s2. do you expect magnesium to be a metal, or insulator? explain why. (b) the energy e of a hole in the valance band of a semiconductor is related to its wave vector k by e= a cosa ka, where a is a constant and a is the atomic lattice spacing. if a = 2 x 10-1°m then the fermi wave vector is 2.618 x 10°m-1 and the fermi energy is lev. determine the effective mass of holes at the fermi level. (c) different atoms have different magnitudes and even sign of the hall coefficient. for instance, au is -0.72 and be is +2.44. what properties determine the sign and magnitude of the hall coefficient? (d) a tiny grain of metal is found to exhibit the phenomena of coulomb blockade at room temperature. write down the conditions for coulomb blockade in terms of the charging energy e and and tunnel resistance rt. estimate the size of the grain.