Dr. Danyuo Yiporo//Materials Science and Chemistry//2023
Homework #1-2023
Due on 11th September 2023 (08:00 AM for Cohort A and 9:50 AM for Cohort B).
Exercise (#1)
(20 Points)
(a) Briefly describe the four (4) types of quantum numbers and what they represent. (5 points)
(b) State the Pauli exclusion principle and what it means for the periodic table of elements. (5
points)
(c) State the Hund’s rule and what it means in filling atomic orbitals. Illustrations are welcome.
(5 points)
(d) State the Aufbau Principle and its relations to electronics configuration. Illustrations are
welcome.
(5 points)
Exercise (#2)
(20 points)
(a) Sketch the force-separation curves and the energy separation curves for a typical covalently
bonded solid. Use these curves to explain why many materials exhibit linear elastic
behavior.
(5 points)
(b) The attractive energy for sodium and chlorine ions sodium chloride is given by EA = -A/r,
if A is given by (Z1e)(Z2e)/(4𝜋𝜀𝑜 ), where 𝜀𝑜 is the permittivity of a vacuum (8.85 x10-12
F/m), e is the electronic charge (1.602 x 10-19 C) and Z1 and Z2 are the valences of sodium
and chlorine ions respectively, estimate the attractive energy of sodium and chlorine ions
in NaCl crystals.
(6 points)
(c) By idealizing the force-separation curve as a sinusoidal curve in part (a), derive an
𝑒2
expression for the work of adhesion. Hint: 𝐹𝑛𝑒𝑡 = 4𝜋𝜀
𝑜𝑟
2
.
(d) Briefly explain why beryllium is a metal and chlorine a nonmetal.
Exercise (#3)
(6 points)
(3 points)
(20 points)
(a) Identify which of the following elements is a metal, alkali metal, alkaline metal, inert gas,
halogen, or transition metal. Briefly explain the reasons for your choices (not more than 2
lines).
(5 points)
2 2 6 2 6 7 2
(i) 1s 2s sp 3s 3p 3d 4s
(ii) 1s22s22p63s23p6
(iii) 1s22s22p63s2
(iv) 1s22s22p63s23p63d24s2
(v) 1s22s22p63s23p64s1
1
Dr. Danyuo Yiporo//Materials Science and Chemistry//2023
(b) (i) Describe why it is easier to use Δ𝐺 to determine the spontaneity of a process rather than
Δ𝑆𝑢.
(3 points)
(ii) Under what conditions does Δ𝐺 allow us to predict whether a process is spontaneous.
(2 points)
(c) Steel is coated with a thin layer of ceramic to help protect against corrosion. What do you
expect to happen to the coating when the temperature of the steel is increased significantly?
Briefly explain.
(d) The enthalpy of fusion and entropy of fusion for water are given by ∆𝐻𝑓𝑢𝑠 =
6.01 𝑘𝐽/𝑚𝑜𝑙 and ∆𝑆𝑓𝑢𝑠 = 22.0 𝐽/𝑚𝑜𝑙.K, respectively. Determine the Gibbs free energy
for the melting of the ice at -10℃ and 20℃. Comment on ∆𝐺 with respect to the change in
temperature.
(5 points)
2