Chapter 2

Question 1

The elements listed in the Periodic table can be divided into three categories. Examples

Answer 1

metals (iron), non metals (carbon), semimetals (silicon)

Question 2

Which elemets are the noble metals, and why are they named noble

Answer 2

Copper, silver, and gold (medals). REsistant to corrosion

Question 3

Describe ionic bonding

Answer 3

Atoms of one element give up the electron to another atom of another element

Question 4

What is the difference between noncrystaline and crystaline structures

Answer 4

The atoms in a crystalline structure are located in a regular and repeating lattice position in three dimensions. These possess a long range order which allows high-packing density. The atoms in an amorphous structure do not follow any pattern

Question 5

What is the difference between primary and secondary bonding in the structure of materials

Answer 5

Primary is a strong bonding (Ex: molecule), Secondary bonding is not strong (Ex: general attraction between molecules in material)

Question 6

What are some common point defects?

Answer 6

VAcancy: missing atom, ion-pair vacandy: missing pair of ions, Interstitalicy: distortion in the lattice caused by an extra atom, Frenkel defect: an ion is removed from he regular position and inserted into a interstitial position

Question 7

Define the difference between elastic and plastic deformation in terms of the effect on the crystal lattice structure

Answer 7

Elastic deformation involves a temporary distortion of the lattice structure that is
proportional to the applied stress. Plastic deformation involves a stress of sufficient magnitude to
cause a permanent shift in the relative positions of adjacent atoms in the lattice. Plastic deformation
generally involves the mechanism of slip - relative movement of atoms on opposite sides of a plane in
the lattice

Question 8

How do grain boundaries contribute to the strain-hardening phenomenon in metals?

Answer 8

Grain boundaries block the continued movement of dislocations in the metal during
straining. As more dislocations become blocked, the metal becomes more difficult to deform; in
effect it becomes stronger.

Question 9

Identify some materials that have a crystalline structure

Answer 9

MEtals and ceramics (NOT GLASS), and very few polymers

Question 10

Identify some materials that posses a noncrystaline structure

Answer 10

glass and certain plastics

Question 11

what is the basic difference in the solidification process between crystalline and noncrystalline structures

Answer 11

Crystalline structures undergo an abrupt volumetric change as they transform from liquid to solid state and vice versa. This is accompanied by energy called the heat of fusion that must be added to the material during melting or released during solidification. Noncrystalline material without these things.

Question 12

The basic structural unit of matter is which of the following (a) atom, (b) electron, (c) element,
(d) molecule, or (e) nucleus?

Answer 12

a atom

Question 13

Approximately how many different elements have been identified (one best answer): (a) 10, (b) 50,
(c) 100, (d) 200, or (e) 500?

Answer 13

c 100

Question 14

In the Periodic Table, the elements can be divided into which of the following categories (a) ceramics, (b) gases, (c) liquids, (d) metals, (e) nonmetals, (f) polymers, (g) semi-metals,
and (h) solids?

Answer 14

d metals, e nonmetals, g semimetals

Question 15

The element with the lowes density and smallest atomic weight is which of the following: (a)
aluminum, (b) argon, (c) helium, (d) hydrogen, or (e) magnesium?

Answer 15

d hydrogen

Question 16

Which of the following bond types are classified as primary bonds (three correct answers): (a)
covalent bonding, (b) hydrogen bonding, (c) ionic bonding, (d) metallic bonding, and (e) van der
Waals forces?

Answer 16

a covalent, c ionic bonding, d metallic bonding

Question 17

How many atoms are there in the FCC (face-centered cubic), BCC (Body-centered cubic), and, HCP (hexagonal close-packed) unit cell (a) 8, (b)
9, (c) 10, (d) 12, or (e) 14 (f) 17

Answer 17

FCC: e 14, BCC: b 8. HCP F 17

Question 18

Which of the following are not point defects: (three correct answers): (a)
edge dislocation, (b) grain boundaries, (c) interstitialcy, (d) Schottky defect (ion-pair), (e) screw dislocation, or
(f) vacancy?

Answer 18

c interstitalcy, d Schottky defect, f vacancy

Question 19

Which one of the following crystal structures has the fewest slip directions (therefore more difficult to deform at room temp) (a) BCC, (b) FCC, or (c) HCP?

Answer 19

c HCP

Question 20

Grain boundaries are an example of which of the following types of crystal structure defects (a) dislocation, (b) Frenkel defect, (c) line defects, (d) point defects, or (e) surface defects?

Answer 20

(e) surface defects

Question 21

Twinning is in which of the following (three best answers): (a) elastic deformation, (b) mechanism of
plastic deformation, (c) more likely at high deformation rates, (d) more likely in metals with HCP
structure, (e) slip mechanism, and (f) type of dislocation?

Answer 21

b mechanism of plastic deformation, c more likely at high deformation rates, d more likely with metals with HCP structure

Question 22

Polymers are characterized by which of the following bonding types (two correct answers): (a)
adhesive, (b) covalent, (c) hydrogen, (d) ionic, (e) metallic, and (f) van der Waals?

Answer 22

b covalent, f van der Waals

Question 23

What are the secondary bonds

Answer 23

Dipole forces, London forces, (van der waals for previous two) Hydrogen bonding

Question 24

covalent bonding?

Answer 24

Electrons are shared between atoms

Question 25

Metalic bonding?

Answer 25

electrons shared as electron cloud

Question 26

Dipole forces

Answer 26

Come form molecules that have two atoms that have opposite electric charges. The positive side of the atom attracts the negative side

Question 27

London forces

Answer 27

Force between non-polar molecules, because elctrons are moving rapidly, a gap forms in the atom, and that exposes the proton, making a small positive charge

Question 28

Hydrogen bonding?

Answer 28

Hydrogen atoms are aligned to one side of the atom (or molecule) creating a positive charge (like in water), that atracts the negative charge of other molecules with similar polarity (like water again)

Question 29

Draw BCC structure

Answer 29

has atom at center

Question 30

Draw FCC

Answer 30

has atom on each face

Question 31

Draww HCP

Answer 31

Hexagon, three in middle

Question 32

Types of defects in crystals

Answer 32

point, line, and surface

Question 33

types of point defects

Answer 33

vacancy, interstitalcy, frenkel defect

Question 34

vacancy?

Answer 34

missing atom or ion

Question 35

intersttialcy

Answer 35

extra atom

Question 36

Frenkel

Answer 36

displaced ion. Ion in a place it’s not supposed to be

Question 37

Why do defects happen?

Answer 37

usually while solidifying, grain boundries end up colliding with each other and can’t form propper ones

Question 38

Edge dislocation

Answer 38

Extra palne of atoms

Question 39

types of Line defencts

Answer 39

edge dislocation, screw dislocation

Question 40

screw dislocation?

Answer 40

Spiral within the lattice structure. It looks like an imperfection line

Question 41

Surface defects?

Answer 41

Defects extend in two directions (like shear stress

Question 42

What happens to atoms in elastic strain

Answer 42

they just stretch a bit

Question 43

What happens to atoms in plastic strain

Answer 43

They snap, or rather shift

Question 44

Explain twinning

Answer 44

Another method of plastic deformation,

Question 45

Main differences between crystalline and non crystalline materials

Answer 45

No order of molecules, differen melting and thermal expansion characteristics