Homework problems (1 and 2)

Q&S related to electronic structure of materials lecture
Submit your answers electronically before September 14, 12am.
1) Silicon (Si) and Chlorine (Cl) react with each other. a) What is the chemical
formula of the reaction product (0.25p)? Silicon is group 4 element and will
exhibit, like carbon, sp3 hybridization involving 4 sp3 orbitals at bond angle of
109o. Unlike carbon, silicon cannot make double and triple bonds b) Based on
this describe the geometric arrangement of atoms in a reaction product
between Si and Cl (0.25p). c) do you expect the product to be solid, liquid or
a gas at room temperature (0.5 p)? Motivate your answers.
2) A pure crystalline material (no impurities present) appears red in transmitted
light. a) Explain if this material is a metal, semiconductor or insulator (0.5p),
b) What is an approximate energy band gap of this material (in eV) (0.5p)?