As we know all matters are made of
atoms , there are about 100 kinds of atoms in the universe according to the
periodic table . The properties of materials depends on the atoms and atomic
bond. Therefore, we can generally determine the different behaviors of
The structure of materials is
classified into three types based on size:
1 – atomic structure
2 – microstructure
3 – macrostructure??6
2.1 Atomic structure
The discovery of the inner structure of the atom is one of the most
important scientific discoveries in this century.
All atoms are made up of
three subatomic particles : Protons , neutron and electrons.
These parts have the properties shown in Table1 :
x 10-24 g
x 10-24 g
x 10-28 g
In Table1 the unit was used for atomic mass is (amu).It is more
appropriate than gram for describing masses of atoms . ??6
defined as the surface structure of materials such as thin foils which can be
detected after zooming 25 times at a microscopic level.
The microstructure of the material can affect the mechanical and
physical properties such as strength , ductility , hardness and corrosion
Macrostructure defined as The overall structure of the material and
can be seen by the naked eye. Materials behaves differently based on mass and
density that behavior can be determined based on the atomic bonding , when we
examine a material in solid state at a
microscopic level we can notes visually the higher number of atoms in
comparison with other material with low density in liquid state . based on that
observation we can tell the differences in nature between solid and liquid.
Furthermore, at macro level liquid behaves differently than solid , for example
when you pour water out of a cup you can see the continuous flow of water. ??9