NATURE OF MATERIALS - Materials for Civil and Construction Engineers - page 83

to the bonding and arrangement of the materials at the atomic level. This chap-
ter provides only a broad overview of the subject. For more information, con-
sult references with more in-depth treatments of these subjects.

QUESTIONS AND

PROBLEMS

2.1 Define elastic and plastic behaviors at the micro and macro levels.
2.2 Describe the parts of an atom. Define proton, electron, atomic num-
ber, and atomic mass.
2.3 What are the valence electrons and why are they important?
2.4 Describe the order in which electrons fill the shells and subshells.
2.5 Describe the different types of bonds.
2.6 Why do atoms maintain specific separations?
2.7 Materials are generally classified into three categories based on the
predominant types of bond. What are these three categories and
what are the predominant types of bond in each category? For each
category, provide two examples of common materials used by civil
engineers.
2.8 What is the atomic packing factor? What information do you need to
compute it?
2.9 Describe FCC, BCC, and HCP lattice structures.
2.10 Show for the face-center cubic crystal structure that the unit cell
edge length a and the atomic radius r are related through
2.11 Referring to the BCC lattice structure shown in Figure P2.11

a = 2 2 2r

r

a

a

FIGURE P2.11

a. Determine the number of equivalent whole atoms in the unit cell.
b. Calculate the relation between a and r .
c. Calculate the atomic packing factor of the BCC lattice structure if
the volume of the sphere is 4/3pr 3 .