Midterm 1 (ch.1-3) Flashcards
(53 cards)
1
Q
What are the types of material properties?
A
- mechanical
- physical (electric, magnetic, optical, thermal, elastic, chemical)
- transport
- radiation response
2
Q
What is a structure-insensitive property?
A
one that does not depend on the mass of the substance or system
3
Q
What are examples of structure-intensive properties?
A
- temperature, pressure, density
- elastic modulus
- thermal coefficient of expansion (TCE) - (may change depending on porosity and texturing)
- specific gravity
4
Q
What is a structure-sensitive property?
A
- a property that depends on impurities and the imperfection of the crystal structure of a material
5
Q
What are some examples of structure-sensitive properties?
A
- yield strength
- thermal conductivity
electrical resistivity - fracture toughness
6
Q
What do material sciences and engineering study?
A
- different types of materials
- the structure-property-process relationships
7
Q
What are the different types of materials?
A
- metals
- ceramics/ glasses
- polymers
- composites
- semiconductors
8
Q
What are examples of metals?
A
- iron
- copper
- aluminum
- silver
- gold
9
Q
Metals description
A
atoms located in regularly defined, repeating positions (crystal), have free electrons
10
Q
Metals strengths (pros)
A
- good electrical conductors
- strong
- ductile
11
Q
Define Ductile
A
- term for materials that can absorb energy by “bending” rather than by fracture when subject to external loads
- (able to be drawn out into a thin wire/ plasticity)
12
Q
Metals weaknesses
A
- dense
- moderate temperature resistance
13
Q
Ceramics/glasses examples
A
- sand
- dinnerware
- window glass
- graphite
- sanitary ware (toilets, bathtubs, etc)
14
Q
Ceramics/ glasses description
A
- combination of metallic and non-metallic atoms
- some ceramics are crystalline
15
Q
Ceramics/ glasses strengths (pros)
A
- very strong and moderate density
- high temperature stability
- chemically resistant
16
Q
Ceramics glasses weaknesses
A
- no free electrons (not conductive)
- brittle
17
Q
Polymers examples
A
- nylon
- cellulose
- Teflon
- kevlar
- polystyrene
18
Q
Polymers description
A
- long chain molecules with repeating groups
- can be ductile or brittle
19
Q
Polymers strengths (pros)
A
- low density
- easy to form into complex shapes
- inexpensive
20
Q
Polymers weaknesses
A
- low strength
- temperature sensitive
21
Q
Composites examples
A
- Carbon/carbon
- Carbon/epoxy
- plywood
- steel belted tires
22
Q
Composites description
A
- 2+ materials combined
23
Q
Composites strengths (pros)
A
- strong and rigid
- low density
24
Q
Semi-conductors examples
A
- silicon
- germanium
- GaAs
- CdTe
- InP
25
Semi-conductors description
- bonding and mechanical properties similar to ceramics
- conductive
26
Semi-conductors strengths (pros)
used in electronic and optical devices
27
Define brittle
- unable to absorb energy from external loads by bending
- fracture easily
28
Define conductivity
the ease with which electric charge is transported through a material in response to an external electric field
29
Define stiff
an object is rigid as it resists bending
30
Define crystalline
having atoms or ions arranged on a 3D lattice having long-range order
31
Define amorphous
lacks the long-range order that is characteristic of crystalline solid
- either rubbers or glasses
32
what are the main components of an atom?
protons, neutrons, and electrons
33
What are the properties of an atom determined by?
- the atomic mass number (Z)
- mass of the atom
- spatial distribution of electrons in orbits
- energy of the electrons
- ease of adding or removing an electron to make a charged atom
34
What atomic properties can be changed by an external field?
- spatial distribution of electrons in orbits
- energy of the electrons
- ease of adding or removing an electron to form an ion
35
What kind of characteristics do electrons exhibit?
characteristics of particles and waves
36
What is the principle quantum number?
- n
- integer number (1,2,3...)
- refers to shell/ energy level
- K: n=1; L: n=2; M: n=3
37
What is the Azimuthal quantum number?
- l
- assigned numbers from l=0 (n-1)
- refers to sub-shell
- s: l=0; p: l=1; d: l=2; f: l=3
38
What is the magnetic quantum number?
- m
- assigned numbers between positive and negative l
- total number = (2l+1)
39
What is the spin quantum number?
- M s (M sub s)
- either +1/2 or -1/2
- reflects the different electronic spins of an electron
40
Which quantum numbers are the energy of a shell primarily dependent on?
- n and l
41
What is the periodic table trend of electronegativity?
it increases from left to right and upwards in the periodic table
42
What does electronegative describe; what kind of elements?
elements with high electronegativity (non-metals)
43
What does electropositive describe; what kind of elements?
elements with low electronegativity (metals)
44
What is electronegativity difference? What does it determine?
- the difference between 2 elements' electronegativities
- determines bond type between those elements
45
What change in electronegativity values correspond with different bonds?
>1.7 = ionic bond
0.6-1.7 = polar covalent bond
<0.6 = nonpolar covalent bond
46
What does primary bonding determine?
physical, mechanical, and chemical properties
47
What does primary bonding involve in terms of electrons?
a transfer or sharing of outer electrons
48
Are atoms shared or transferred with ionic bonding?
transferred
49
What are some properties of ionic bonds?
- non-directional bond
- low electrical conductivity
- brittle
- high melting temperature
- happens when ions of opposite charge attract as a result of coulombic attraction
50
Are electrons transferred or shared in covalent bonds?
shared
51
What are some properties of covalent bonds?
- directional bonds
- low electrical conductivity
- very hard/strong
- high melting temperature
- > or equal to 4 valence electrons
52
Are electrons shared or transferred in metallic bonds
shared
53
What are some properties of metallic bonds?
- non-directional bonds
- good electrical conductivity (free electrons)
- ductile and opaque
- <3 valence electrons
