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NE 125 > Week 1 > Flashcards

Week 1 Flashcards

1
Q

What defines material properties?

A

Structure, ‘arrangement of internal components’

can be subatomic, atomic, nanostructure, microstructure or macrostructure

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2
Q

What is atomic mass?

A

Sum of masses protons and neutrons within the nucleus

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3
Q

What is are Isotopes?

A

Atoms with two or more difference atomic masses

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4
Q

What is atomic weight?

A

Weighted average of atomic masses of the atom’s naturally occurring isotopes

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5
Q

How do we calculate average atomic weight?

A

Average atomic weight = sum of [fraction of occurrence multiplied by atomic weight of isotope]

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6
Q

Definition of Quantum mechanics

A

Laws/principles governing atomic and subatomic entities

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7
Q

What is the Wave-Mechanical Model

A

Electron considered to exhibit both wave and particle-like characteristics

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8
Q

How does the Wave-Mechanical Model define position?

A

not perceived as a particle moving a discrete orbital but but by probability distribution/electron cloud (electron at various locations around the nucleus)

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9
Q

What are the four quantum numbers and their symbols?

A 
Principle Quantum 
Size/Primary Number - n
Shape/Secondary Quantum Number - l (n-1)
Orientation - ml (-l to +l)
Spin - ms (+1/2 or -1/2)
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10
Q

What are the letter designations for the values of l

A 
0 - s
1 - p 
2 - d 
3 - f
4 - g
5 - h
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11
Q

What is the ground state?

A

When all electrons in atom occupy lowest possible energies

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12
Q

What is electron configuration?

A

(structure of an atom) manner in which these states are occupied
i.e Oxygen(O)
1s2 2s2 2p4

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13
Q

What is the Pauli Exclusion Principle?

A

No electron state can hold more than two electrons that must have opposite spins

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14
Q

What is Electron State?

A

Values of energy that are permitted electrons

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15
Q

Trend for electronegativity

A

Increases going to the right and up(Highest EN - F 4.0)

Decreases going to the left and down(Lowest EN - Fr/Cs 0.7)

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16
Q

What is a property?

A

Trait in terms of kind and magnitude of reaction to an imposed stimulus.

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17
Q

What are the 6 property classifications?

A

1) Mechanical
2) Electrical
3) Thermal
4) Magnetic
5) Optical
6) Deteriorative

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18
Q

Mechanical properties?

A

Applied load; strength, stiffness, resistance to fracture, elasticity.

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19
Q

Electrical properties?

A

Applied electric field; conductivity; dielectric constant.

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20
Q

Thermal properties?

A

Temperature change, expansion, heat capacity.

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21
Q

Magnetic properties?

A

Applied magnetic field, susceptibility, magnetization.

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22
Q

Optical properties?

A

Electromagnetic radiation, reflectivity, refraction, absorption.

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23
Q

Deteriorative properties?

A

Chemical reactivity, corrosion, electrode potential.

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24
Q

What defines properties?

A

Structure; arrangement of internal components.

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25
Q

Subatomic scale?

A

Electrons within atoms; energies and interactions with nuclei.

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26
Q

What’s the atomic level?

A

Organization of atom to form molecules or crystals.

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27
Q

Nanostructure level?

A

Atom aggregates < ~100nm (nanoparticles).

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28
Q

Microstructure level?

A

Structural elements viewed under microscope.

100nm < size < 1 + mm

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29
Q

Macrostructure level?

A

Structural elements viewed by naked eye

1+mm < size < 1+ meter

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30
Q

What’s the modified paradigm?

A

Processing —> Structure —> Properties —> Performance —> Reuse/Recyclability

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31
Q

What’s the Classic Paradigm?

A

Processing —> Structure —> Structure —> Properties —> Performance

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32
Q

What are the 3 primary Solid Materials?

A

Metals, ceramics, polymers (Based in chemical makeup and atomic structure)

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33
Q

What’s a metal material?

A

Mainly metallic elements (nonmetallic in relatively small amounts); atoms arranged in orderly manner

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34
Q

What’s a ceramic material?

A

Compound between metallic and non-metallic (most frequently oxides,nitrides and carbides); Tetrahedral like structures.

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35
Q

Ceramic vs glass?

A

Ceramic crystalline vs Glass non- crystalline

36
Q

What are Polymer materials?

A

Organic compounds chemically based on carbon, hydrogen, and other nonmetallic elements (O, N, Si); large molecular structures chain-like with carbon atom backbone.

37
Q

What are the the different properties of metals, ceramics, and polymers?

A

Add pic later (lec 1, slide 29)

38
Q

What’s a composite?

A

Composed of 2 or more individual materials to achieve combination of properties not displayed by any single material; best characteristics of each.

39
Q

What’s a semiconductor?

A

Intermediate electrical properties (b/w metals and ceramics/polymers).

Sensitive to presence of tiny concentrations of impure atoms.

Change silicon behaviour by mixing a small amount of impurity (doping)

Work due to imbalance of electrons

40
Q

Biomaterials?

A

Used to fix defects, repair or replace defective organ in body.

Inert materials implanted into body to function in a safe, reliable and physiologically safe manner.

Biocompatible; not toxic; desired properties

41
Q

What are the 4 advanced Materials?

A

Semiconductors, bio materials, nano materials and smart materials

42
Q

Smart materials?

A

Have the ability to sense changed in environment and respond in predetermined manners.

43
Q

Nano materials?

A

Distinguished based in size.

Bottom-up approach as opposed to top-down approach- scanning probe microscopes.

44
Q

What is atomic mass unit?

A

Amu (unit used to compute atomic weight).

45
Q

Mass of an electron?

A

9.11 x 10^-31 kg

46
Q

Mass of proton/neutron?

A

1.67 x 10^-27 Kg

47
Q

Avogadro’s number?

A

6.022 x 10^23

48
Q

Magnitude of charge of electron/proton?

A

1.602 x 10^-19 C

49
Q

What did the Bohr Model explain?

A

Position of electron orbitals and quantized energy levels.

50
Q

What is unique about particle position?

A

Position is not perceived as particle moving in discrete orbital but by probability distribution/electron cloud (electrons at various locations around the nucleus).

51
Q

How many electrons are in a S-orbital?

A

S-orbital is spherical with 2 electrons.

52
Q

How many electrons in Pi-orbital?

A

6 electrons in 3 subshells with 2 electrons in each.

53
Q

What is interatomic bonding

A

how to atoms interact when they are brought close together from an infinite separation
Attracted - Fa > Fr
Repelled - Fa < Fr
Equilibrium Fa = Fr

54
Q

What does Fa depend on

A

Depends on the type of bonding between the atoms

55
Q

What causes Fr

A

Due to electron cloud surrounding atom at small r values

56
Q

When is the net force of fa and fr = 0

A

at ro (r knot)

At approximately 0.3nm.

57
Q

Force-energy relationship for two atoms

A

E = integral of F dr
E net = Ea + Er

Other way around:
F = dE/dr

58
Q

Types of bonds

A

Primary:

  1. Ionic
  2. Covalent
  3. Metallic

Secondary/Van Der Waals

59
Q

What is ground state?

A

When all electrons in atom occupy lowest possible energies (most stable)

60
Q

What’s a valence electron?

A

Those that occupy the outermost shell( can be transferred or shared with another atom).. if filled, configuration is stable.

Aka all electrons outside of nearest inert gas.

61
Q

Conditions for attraction?

A

FA > FR

62
Q

Conditions for repulsion?

A

FA < FR

63
Q

What are the conditions for equilibrium?

A

FA = FR

64
Q

What is r?

A

Separation between 2 atoms.

65
Q

When is force negligible?

A

As r approaches infinity.

66
Q

What is E0(Energy knot)?

A

Bonding energy. Aka minimum require energy to separate 2 atoms to an infinite separation.

67
Q

Is ionic bonding directional?

A

No it is non-directional

68
Q

What does Non-directional mean?

A

Magnitude of bond is same in all directions.

69
Q

What’s an ionic bond?

A

Metal + Non-metal.

Transfer of valence electron.

70
Q

What’s valency?

A

Combining capacity of an atom to share/transfer electrons.

71
Q

How many valence electrons are in Fe? [Ar]3d^6 4s^2

A

8 electrons (outside of [Ar])

72
Q

Ionic bonding attractive energy equation?

A

EA = -A/r

A = (Z1)(Z2)(e^2)/4(pi)(€0)

Z is absolute # valences
€0 is 8.85x10^-12 F/m

e = 1.602 x 10^-19 C

73
Q

Ionic bonding Repulsive energy equation?

A

ER = B/r^n

74
Q

What does directional mean?

A

Exists only in one direction-b/w atoms sharing electrons.

75
Q

Is covalent bonding directional?

A

Yes due to differences in electronegativites of bonded electrons

76
Q

What’s covalent bonding(hybridization)?

A

Overlapping of 2 or more orbitals.

Ex sp2 and sp3

77
Q

What is metallic bonding?

A

Metals and their alloys, valence electrons not bound to any particular atom, sea of electrons/electron cloud (keeps structure in equilibrium).

78
Q

Is there any atom bonding in metallic bonding?

A

No, sea of electrons keep atoms together

79
Q

Is metallic bonding directional?

A

No, electron act like glue

80
Q

Is primary or secondary bonds stronger?

A

Primary bonds are stronger as they are physical bonds.

81
Q

What’s a secondary bond?

A

Bond that exists between all molecules (presence masked by primary bonds), experience by stable electron configuration atoms, arises from atomic/molecular electric dipoles.

82
Q

What causes secondary interatomic bonding?

A

Dipole

83
Q

What’s a dipole?

A

Separation of positive and negative within the same atom/molecule

Van Der Waals exists between two such molecules

84
Q

The 3 dipole interactions?

A

1) Between induced dipoles(temporary/fluctuating)
3) Between induced dipoles and polar molecules
3) Between polar molecules(permanent)

85
Q

What’s a polar molecule?

A

Molecule with permanent dipole.

86
Q

What’s the percent Ionic Character equation?

A

%IC = {1-exp[-(0.25(XA-XB)^2]} x 100

XA = electronegativity for A
XB = electronegativity for B

NE 125 (3 decks)

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