Lecture week 1& 2 :atomic structure & Quantum numbers Flashcards
Four components of materials science
1.Structure ;Electronic/Bonding
✓ Atomic/Molecular
✓ Crystallographic characteristics
✓ Micro- and Macro-structur
2.Processing:
✓ Magnetic
✓ Optical
✓ Deteriorative✓ Melting
✓ Smelting
✓ Sintering
✓ Chemical
✓ Synthesis
3.Perfomance; ✓ Cost
✓ Longevity
4.Properties :
Mechanical properties
➢ Response to mechanical forces
➢ Many materials are subjected to forces or loads when in service
➢ It is necessary to know the characteristics of the material and to design the
materials
e.g. stiffness, strength, hardness, ductility, toughness,
electrical properties
- response to electrical fields
Conductivity or resistivity
Optical properties
— Optical properties
➢ response to absorption, transmission and scattering of light
Transmittance:
- Aluminum oxide may be transparent, translucent, or opaque depending on
the material structure.
Deteriorative characteristics
elate to the reactivity of materials in contact with environment,
e.g., corrosion
* Metal loss caused by dissolution or formation of nonmetallic scale / film
* The corrosion proves is oxidization and reduction reaction (contacts with gas
or liquids), e.g., rust of steel and copper
* Most metals and alloys are subject to oxidation or corrosion because they are
more stable in an ionic state than as metals, except Au and Pt.
Metal
Thermal properties
related to transmission of heat capacity
Magnetic Properties
Response to magnetic fields
Magnetic Storage :
* Important in the area of information storage
* Magnetic recording — universal technology
* e.g. computers, hard disk credit debit
cards (magnetic stripes),
* In computers
➢ Primary memory — semiconductor elements
➢ Secondary memory — HDD
▪ Recording medium is magnetized by write head
▪ Capable of storing larger quantities of information
▪ Transfer rates are slower
▪ Lower cost
Three types of INTERATOMIC Bonds
1.Ionic Bonding
2.Covalent Bonding
3.Metallic bonding
Properties of ionic solids
- Hard and brittle
– Strong bonds resist deformation
– Bonds can not rearrange → brittle -
Electric and thermal insulator in
solid state
– No free electrons.
Ionic solids do not bend
Ceramic Space Shuttle
Tile: Low thermal
conductivity protects
shuttle during re-entry
Civalent bonding
In covalent bonding, stable electron configurations are assumed
by the sharing of electrons between adjacent atoms
Covalent Bonding is directional meaning….
i.e. between specific atoms
– May only exist in the direction between
one atom and another that participate in
the electron sharing.
Quantum numbers n,(Principal Energy Levels)
It shows the number of states within each subshell, with values of 1,2,3…..
Orbital Quantum number
This signifies the subshell which is denotes by a lowercase letter-an s,p,d or f.Values 0,1….(n-1).
l=0- s ;l=1-p; l=2-d ,l=3-f
Magnetic quantum number ‘m1”
Determines the number of energy states for each subshell, total number 2l+1
ms (Spin Quantum number):
Associeated with each electron is a spin moment,which must be oriented either up or down
