CHAPTER 3

Question 1

How does the type of packing of atoms relate to the theoretical minimum bonding energy?

Answer 1

atoms of dense, ordered packing (ie metals) tend to be closer to their minimum bonding energy…MORE STABLE

Question 2

Examples of crystalline materials

Answer 2

metals
many ceramics
some polymers
plastic bag

Question 3

Examples of noncrystalline (amorphous) materials

Answer 3

complex structures
rapid cooling
glass

Question 4

What is a unit cell?

Answer 4

The simplest/smallest repeat unit of a crystal at the atomic/molecular level

Question 5

Why do metals pack densily?

Answer 5

Bonds between metal atoms are nondirectional
Nearest neighbor distance tends to be small in order to lower bond energy
High degree of shielding from free electron cloud

Question 6

Rank densities from greatest to lowest of the material types

Answer 6

(greatest) metal > ceramics > polymers

Question 7

What is anisotroy?

Answer 7

Property value depends on crystallographic direction of measurements

Question 8

What is polymorphism/Allotropy?

Answer 8

Crystal structures that can change

Question 9

What is a family of directions?

Answer 9

all directions that are crystallographically equivalent (have the same atomic spacing)

Question 10

What is a family of planes?

Answer 10

all planes that are crystallographically equivalent (have the same atomic packing)