The Structure Of Materials

Front 1

Number of Elements

Back 1

100+ elements, 87 known metals

Front 2

Structure

Back 2

Relates to the arrangement of a materials internal components

Front 3

Density formula

Back 3

Front 4

Transparency indicates what kind of crystal structure?

Back 4

Completely See through - Single Crystal

Front 5

Translucent appearance indicates what kind of crystal structure?

Back 5

Polycrystalline - partly see through

Front 6

Opaque appearance indicates what kind of crystal structure?

Back 6

Polycrystalline with porosity - not see through

Front 7

A-iron: name, structure and formation temperature

Back 7

Ferrite, forms below 910°C, BCC

Front 8

Gamma iron: Name, formation temperature and Crystal structure

Back 8

Austenite, forms above 910°C up to 1,400°C, FCC

Front 9

What are metals?

Back 9

Comprised of one or more metallic elements (eg Fe, Al, Cu, Ti, Au and Ni) and small amounts of non-metallic elements (C, N, O)

Regular atomic arrangement

Relatively dense relative to ceramics and polymers

Front 10

Metals - Mechanical Properties

Back 10

Stiff

Strong

Ductile

Fracture Resistant

Front 11

Metals - Non-mechanical properties

Back 11

Free Electrons

Good electrical and thermo conductor

Desirable Magnetic properties

Front 12

What are Ceramics?

Back 12

Oxides, Nitrides and Carbides

Front 13

Ceramics - Mechanical Properties

Back 13

Stiff

Strong

Hard

Brittle

Engineered with improved fracture resistance

Front 14

Ceramics - Other properties

Back 14

Insulating (heat and electrical)

Can be Transparent, translucent or opaque

Magnetic Behaviour

Front 15

What are Polymers?

Back 15

Organic compounds based on C, H, and other non-metallic elements (eg O, N, Si) forming large chain like structures with backbone of C atoms.

Plastic and Rubber materials

Front 16

Examplea of Polymers

Back 16

Polyethalene (PE)

Nylon

Poly-vinyl-chloride (PVC)

Polycarbonate (PC)

Polystyrene (PS)

Silicone Rubber

Front 17

Polymers - Mechanical Properties

Back 17

Low Densities

Ductile

Plastic

Front 18

Polymers - Other properties

Back 18

Chemically inert

Tendency to soften/decompose

Low electrical conductivity

Non-magnetic

Front 19

What are Composites and why are they made?

Back 19

Combinations of properties that are not displayed by a single material.

To incorporate the best characteristics of each of the components materials

Front 20

Synthetic composite examples

Back 20

Fiberglass

Carbon Fiber-Reinforced Polymers (CFRP)

Front 21

Natural Composite Examples

Back 21

Wood

Bone

Front 22

Mass of Proton/Neutron

Back 22

1.67 × 10^(-27) kg

1 amu

Front 23

Mass of Electron

Back 23

9.11 × 10^(-31) kg

Front 24

Charge of Proton & Electron

Back 24

Proton:

+ 1.602 × 10^(-19) C

E:

- 1.602 × 10^(-19) C

Front 25

Atomic mass unit

Back 25

1 amu is defined as 1/12 of the atomic rest mass of C12

Front 26

Atomic Weight

Back 26

The weighted average of the masses of each naturally occurring isotope for a particular element.

Front 27

Value of 1 mol

Back 27

6.022 × 10^23

Front 28

Bohr Model of the Atom

Back 28

Electrons have discrete orbital

Electron energies are quantized (have specific energy levels/states)

Front 29

Wave-Mechanical model of the atom

Back 29

Electron has both wave AND particle-like characteristics, position described by probability distribution (electron cloud).

Front 30

What are the atomic quantum numbers?

Back 30

The four parameters to describe an electron:

1) Size of electrons probability density (electron cloud)

2) Shape of the electron cloud

3) Spatial Orientation of the cloud

4) Number of states within each subshell

Front 31

The maximum number of subshells is..

Back 31

..equivalent to the shell number

n=1, 1 subshells possible

n=2, 2 subshells possible

Front 32

Each subshell can hold a maximum of..

Back 32

4L+2 electrons

Front 33

Electron energy levels: n &L

Back 33

Front 34

Atom is said to be in it's ground state when..

Back 34

.. all the electrons occupy the lowest possible energy levels

Front 35

What does Electron Configuration Describe?

Back 35

How Electrin states are occupied

E.g. Hydrogen: 1s1

1s2 2s2 2p6 3s1

Front 36

Valence electrons

Back 36

Valence electrons occupy the outermost shell and are the only electrons to participate in bonding (hence define physical and chemical properties)

Front 37

Interatomic seperation between two atoms net force graph.

Back 37

Front 38

Equilibrium spacing

Back 38

The distance (r0) between two atoms where the sum of the attractive and repulsive force (net force) is zero. (For many atoms, r0 ~~ 0.3 nm)

Front 39

The dependence of net potential energies on interatomic separation for two isolated atoms graph.

Back 39

Front 40

Minimum in the net energy curve corresponds to what position.

Back 40

Equilibrium spacing - r0

Front 41

Bonding energy (E0)

Back 41

The energy required to separate the two atoms to infinity.

Front 42

Large E0 (bonding energy) indicates..

Back 42

..high melting temperature

Front 43

Shape of interatomic separation curve indicates..

Back 43

Elastic moduli

Front 44

Linear coefficient of thermal expansion is related to the shape of what curve

Back 44

E0 - r0 curve

Front 45

Types of Interatomic Bonding

Back 45

Ionic

Covalent

Metallic

Front 46

Ionic bonding Constituents

Back 46

Always found in materials comprised of metallic AND non-metallic elements (eg. NaCl)

Front 47

Ionic Bonding Mechanism

Back 47

Electrostatic forces between ions created by the donation and acceptance of a valence electron

Front 48

Ionic Bonding properties

Back 48

Non-directional

Predominant in ceramics

High bind energies (600 to 1500 kJ/mol)( 3 to 8 eV)

High melting temp

Hard and Brittle

Electrically and thermally insulating

Front 49

Covalent Bonding constituents

Back 49

Non-metallic elements

Front 50

Covalent Bonding Mechanism

Back 50

Atoms obtain a stable electron strucutre by sharing electrins between adjacent atoms, strength determined by electronegativity difference

Front 51

Covalent Bonding Properties

Back 51

Directional bonding

May be strong (eg. Diamond) and hard (MT >3550°C) or weak (Bismuth) (MT: 270°C)

Found in Polymers

Front 52

Metallic Bonding Constituents

Back 52

Metals

Front 53

Metallic Bonding Mechanism

Back 53

Sea of electrons (drifting) unbound to each of the positively charged cores.

Front 54

Metallic Bonding Properties

Back 54

Strong and weak bonds (0.7 eV for Hg or 8.8 eV for W)

Good conductors

Front 55

Secondary/Van Der Waals bonding arrises are a result of..

Back 55

Atomic/Molecular dipoles

Front 56

When do Dipoles exist

Back 56

When there is a separation between the positive and negative part of a atom/molecule (polar). Typically quite weak (0.1 eV) and arise due to Coulombic attraction.

Front 57

Crystalline material

Back 57

A Crystalline material is one in which the atoms are situated in a repeating or periodic array over large atomic distances

Front 58

Amorphous material

Back 58

A amorphous material is one in which the atoms are NOT situated in a repeating or periodic array over large atomic distances

Front 59

Random vs. Regular Packing

Back 59

Dense, Regular Packing, is when the atoms are at equilibrium spacing/lowest potential energy

Front 60

Crystal structure

Back 60

The way in which atoms, ions, or molecules are spatially arranged

Front 61

Simple Cubic (SC) Properties

Back 61

Lattice Parameter = a = 2R

Co-ordination Number = 6

Atoms/unit cell = 1

Front 62

Elements with Simple Cubic Structures

Back 62

Polonium (Po)