• Subatomic level
Electronic structure of individual atoms that
defines interaction among atoms (interatomic
bonding).
• Atomic level
Arrangement of atoms in materials (for the same
atoms can have different properties, e.g. two forms
of carbon: graphite and diamond)
• Microscopic structure
Arrangement of small grains of material that can
be identified by microscope.
• Macroscopic structure
Structural elements that may be viewed
with the naked eye.
Properties:
Properties are the way the material responds to the environment and external forces.
Mechanical properties – response to mechanical forces, strength, etc.
Electrical and magnetic properties - response electrical and magnetic fields, conductivity, etc.
Thermal properties are related to transmission of heat and heat capacity.
Optical properties include to absorption, transmission and scattering of light.
Chemical stability in contact with the environment - corrosion resistance.
Types of Materials:
Let us classify materials according to the way the atoms are bound together.
Metals: valence electrons are detached from atoms, and spread in an electron sea that "glues" the ions together. Strong, ductile, conduct electricity and heat well, are shiny
if polished.
An alloy is a combination of two or more metals usually produced to have new materials with improved properties.
Alloys like : Cu-Zn (brass) , Fe-C (steel) , Sn-Pb (solder) .
Semiconductors: the bonding is covalent (electrons are shared between atoms). Their electrical properties depend strongly on minute proportions of contaminants.
Examples: Si, Ge, GaAs.
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
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