a. b. Figure 1 shows a ball-and-stick model of a very small crystal of a-Polonium. Answer the questions. Source: https://www.tf.uni-kiel.de/matwis/amat/iss/kap_5/illustr/s5_4_1a.html (10 March 2022) What is the lattice parameter of a-Polonium? Report your answer in units of nanometers. C. Figure 1: Z Answer: What is the distance from left to right (along the y axis) for the whole crystal? Report your answer in units of nanometers. Answer: If the top portion of the crystal is sheared by one unit of b from left to right, how many bonds will be broken to achieve this outcome? Answer:

Coulombs Law describes the interaction between two charges and varies by the magnitude of these charges and inversely with the distance between them. For atoms, we'll label the charges as the nuclear charge and electron charge. 9192 9nuclelec As you go up in atomic number (Z), the number of protons in the nucleus increases, making the charge on the nucleus increase, so that in general. qnuc = Z ·(+1) However if we think only of the electrons in the outermost shells (valence electrons), they do not see the full strength of the nuclear charge because it is partially shielded (or canceled out if you prefer) by the core electrons. So we define something called effective charge. Shielding Experiences net charge of about 1+ Nucleus Effective Charge = # of protons Zeff = Z – core # of core electrons In general, Zeff increases as you go across in the periodic table. 1. Fill out the following table to verify that effective charge increases as you go across a row. Element Na Mg Al Si P S CI Ar…

Q#02. Answer the followings: (a) Elucidate the salient features of reciprocal lattice and how does it help to investigate the crystal structures.

For the shown crystal structure, write down (a) the Bravais lattice and (b) the basis of the primitive unit cell. For this structure a=b= c and a=B=y%3D90°. The green (A) atoms at the vertices; blue (B) atom at the center, pink (C) atoms are the centers of two opposite faces; and brown (D) atoms at the centers of four edges of the unit cell. Note that the a, b and c translation vectors are along the positive x, y and z axes, respectively, as shown. COD