Midterm 1 Review

Question 1

Metals are characterized by which one of the following bonding types:

(a) covalent
(b) hydrogen
(c) ionic
(d) metallic
(e) van der Waals

Answer 1

Metallic

Question 2

fill in blank

The nucleus of an atom contains _____ & _______

Answer 2

Protons; Neutrons

Question 3

An element with electron configuration has how many electrons?
1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6)

Answer 3

18

Question 4

What is the the electron configuration for an inert gas?

Answer 4

1s^(2) 2s^(2) 2p^(6) 3s^(2) 3p^(6) 3d^(2) 4s^(2)

Question 5

The electrons that occupy the outermost filled shell are called ________ electrons.

Answer 5

valence

Question 6

Atomic bonding type in ceramics is: _____ and ________

Answer 6

Ionic; Covalent

Question 7

Atomic bonding in Semi-metals (metalloids) is:

Answer 7

mixed covalent-metallic

Question 8

Materials whose constituent particles bound by which type of bond are generally expected to have the highest melting temperature?

Answer 8

ionic

Question 9

How many atoms are there in the body-centered cubic (BCC) unit cell ?

Answer 9

9

Question 10

How many atoms are associated (per unit cell) with each face-centered cubic (FCC) unit cell or how many atoms may be assigned to a FCC unit cell?

Answer 10

4

Question 11

How many atoms are there in a hexagonal close-packed (HCP) unit cell?

Answer 11

17

Question 12

True or False: The coordination number and the atomic packing factor for the HCP crystal structure are the same as for FCC.

Answer 12

True

Question 13

Fill in blank with a numerical value

The atomic packing factor (APF) for BCC structure is ____.

Answer 13

0.68

Question 14

In materials exhibiting mixed bonding, the percent ionic character (%IC) between two elements A and B depends on _________ ________.

Answer 14

electronegative values

Question 15

Bragg’s law is used to determine:

Answer 15

Inter-planar spacing

Question 16

The equilibrium number of vacancies, N_v, for a given quantity of material depends or increases with temperature according to :

Answer 16

exponentially

Question 17

True or False: In metals, there are significantly more vacancies than self-interstitials.

Answer 17

True

Question 18

True or False: The solute is an element or compound present in the greatest amount.

Answer 18

False

Question 19

skipped #19 because it contains image

just write “skip”

Answer 19

skip

Question 20

May have more than 1 answer.

Which of the following statements about crystal structures are true?

(a) metals are almost never in crystal form
(b) amorphous materials do not have long range order
(c) FCC and HCP materials, if made from the same atoms, would have the same density,
(d) BCC and HCP have the same atomic packing factor

Question 21

A solid-solution alloy is _______

Question 22

Which of these is a linear defect?

(a) vacancy
(b) interstitual
(c) edge dislocation
(d) substitutional

Answer 22

edge dislocation

Question 23

True or False: Solid solution are also formed in ceramics

Answer 23

True

Question 24

The maximum allowable concentration of impurity atoms in interstitual solid solution is:

Answer 24

less than 10%

Question 25

Which of these defects occur only in ceramics?

a) a screw dislocation
(b) A Schottky defect
(c) edge dislocation
(d) staking faults

Question 26

True or False: Property values are independent of crystallographic direction of measurement in isotropic materials.

Answer 26

True

Question 27

What are the three basic categories of materials?

Name the fourth category of materials

Answer 27

1) Metals
2) Ceramics
3) Polymers
4) Composites

Question 28

Expain the distintive characteristics of each type of material. (From the three basic types of materials)

Give two example for each materials.

Question 29

Define a unit cell

Question 30

Explain the difference between a polycrystalline material and a single crystal

Question 31

Define and describe: theoretical density

Name the factors that determine the theoretical density of a metal

Question 32

Define and describe: planar density

Question 33

Define and describe: linear density