study guide

Question 1

an atom is composed of ______; __________ and ___ except ___________(which element), the nucleus of which does not have neutron

Answer 1

proton; neutron, electron, hydrogen

Question 2

atomic number is equal to the number of ______ in a nucleus of an atom; and the number of _________ of a neutral species

Answer 2

protons

electrons

Question 3

the electrons that occupy the outermost filled shell are also called __________ electrons

Answer 3

valence

Question 4

the predominant type of bonding for titanium is __________

Answer 4

metallic

Question 5

electrons tend to occupy the ______ available energy states

Answer 5

lowest

Question 6

what does electronegativity represent? metallic elements or non metallic elements?

Answer 6

?non metallic

Question 7

to form ionic bonding ______ electronegativity difference between two elements are required; what about to form covalent bonds?

Answer 7

large are required????

small ones are required for covalent bonds

Question 8

what is the primary bonding of NaCl? what about CO2? what about Fe?

Answer 8

ionic —> covalent —–> metallic

Question 9

secondary bonding arises from the interactions among __________, typically, __________ have significant amount of secondary bonding

Answer 9

dipoles.

polymer

Question 10

which has higher bonding energy?

Answer 10

primary bonding

Question 11

high bonding energy usually leads to ______ thermal expansion and _________ melting temperature

Answer 11

low thermal expansion

high melting temperature

Question 12

crystalline structures and amorphous structures, which usually has more dense packing atoms? which have orderly structures?

Answer 12

crystal - have high density

crystal will have orderly structures

Question 13

most engineering materials are ________

Answer 13

polycrystals

Question 14

properties of ____ may/or may not vary with direction; while properties of _____________ vary with directoin

Answer 14

polycrystals- may or may not vary with direction

single crystal vary with direction

Question 15

two steps of solidification process are ________ and __________

Answer 15

nuclei form and nucleic growth

Question 16

atoms at grain boundary area have high reactivity and mobility

Answer 16

true

Question 17

the equilibrium concentration of point defects increases with temperature (t/F)

Answer 17

true

Question 18

know structures of three different types of point defects

Answer 18

substitutional, interstitial, vacancies

Question 19

in substistitutional solid solution, the impurity atoms occupy the atomic sites in crystal lattice (t/F)

Answer 19

T

Question 20

Ni in Cu is interstitial solid solution (t/f)

Answer 20

false its substitutional. because atom radi are to close in size

Question 21

in __________ dislocation, the burgers vector is parallel to the dislocation line; in _________ dislocation, the dislocation motion shows spiral pathway; in _______ dislocation, there is an extral half-plane of atoms. to describe the lattice distortion caused by dislocations; the parameter _________ is used

Answer 21

line dislocation

skew dislocation

edge dislocation

burgers vector

Question 22

diffusion phenomenon could only occur between different materials (t/f)

Answer 22

false. interdiffusion

Question 23

to form substitutional solid solution, _______________ sites in crystal are needed becasue of __________ mechanism

Answer 23

vacancies sites

because of vacancy mechanism

Question 24

two diffusion mechanisms introduced in the class are _______ and _________

Answer 24

vacancy and intersitial

Question 25

vacancy diffusion and interstitial diffusion, which one needs a higher activation energy?

Answer 25

vacancy diffusion

Question 26

vacancy diffusion rate depends on ____________ and ____________

Answer 26

activation energy, and number of vacancies