ENT147/3 Engineering Materials
QUIZ 1
17 October 2016 : 1 hour
1. Element C, Al and Fe have an atomic number (Z) of 6, 13,
and 26, respectively. Show the electron configuration of the
elements by utilizing orbital box diagram.
(3 marks)
2. What are primary and secondary bond? Give an example for
each.
(4 marks)
3. Rhodium has an atomic radius of 0.1345 nm and a density of
12.41 g/cm3. Determine whether it has an FCC or BCC crystal
structure. Given ARh = 102.91 g/mol and NA is Avogadro’s
number. Use density
(3 marks)
ANSWERS
1. Element C, Al and Fe have an atomic number (Z), 6, 13, and 26,
respectively. Show the electron configuration of the elements
by utilizing orbital box diagram.
Element C : 1s2 2s2 2p2
Element Al : 1s2 2s2 2p6 3s2 3p1
Element Fe: 1s2 2s2 2p6 3s2 3p6 4s2 3d5
3 Marks
2. Type + Example
• Ionic
• Covalent
• Metallic
• Permanent or Fluctuating Dipoles
Chapter 3 -
Chapter 3 - 4
Atomic Packing Factor: FCC
• APF for a face-centered cubic structure = 0.74
maximum achievable APF
Close-packed directions:
length = 4R = 2 a
2a
a
Adapted from
Fig. 3.1(a),
Callister &
Rethwisch 8e.
Unit cell contains:
6 x 1/2 + 8 x 1/8
= 4 atoms/unit cell
atoms
volume
4
3
p ( 2a/4 )
4
unit cell
atom
3
APF =
volume
3
a
unit cell
Chapter 3 - 5