شرح درس
Nanotechnology
CHEMISTRY - Secondary 1
In This part we will study
There are some derived words from the SI basic units differ from each other’s by powers of ten (decimal exponent 10n).
Examples:
Calculate the value of: Solutions :
42.3 millimeter by meter unit. 42.3 nm= 42.3 x 10-3 = 0.0423 m
0.03 second in Nano sec. unit. 0 .03 s = 0 .03 x 109 = 3 x 107 ns
497.3 mg in microgram unit. 497.3 mg= 497.3 x 103 μg
10 millimeter in nanometer unit. 10 mm= 10 x 106 = 107 nm
Nano scale: is the scale of the extremely small particles.
Nanometer: is used as a measuring unit for very minute particles like atoms and molecules, as shown in the following figures:
Critical Nano volume: is the volume in which the unique Nano properties of substance appear and it is less than 100 nm.
Examples of Nano properties:
A: The change of gold color according to the change of the Nano volume:
- It's common that gold has a bright Yellow color, but on reducing its particles volume to the Nano volume, it takes different colors like:
Red, orange, green or blue according to its Nano volume.
- The change of gold color on changing its volume from macro scale into Nano scale...
Because the reaction of gold particles in Nano scale with light differs from its reaction with light in macro scale.
B: The change of the copper hardness according to the Nano volume:
- The hardness of copper increases by decreasing the volume of its particles to be in Nano volume.
- The unique (unusual) properties of Nano substances are due to the relation (ratio) between the surface area and its volume.
The relation between the surface area and the volume of a cube.
On dividing a cube of a side length of 1 cm to many cubes, the total surface area of cubes increases, while the total volume of cubes still constant, as shown in the following table :
- With more division of the cube, the ratio between the surface area and the volume increases:
When the particles of the substance become in Nano volume, the ratio between the surface area and the volume will increase to a very large value.
So, it will provide the substance with new and unique physical and chemical properties.
- It is clear that fine powdered sugar dissolves faster than a block cube in the same amount and at the same temperature, because sugar powder has a greater ratio between the surface area and the volume than that of a sugar cube. So, more number of molecules will be exposed to the dissolving process at the same time.
Best wishes to you
Mr.Ahmed Elbasha
كيمياء الصف الاول الثانوي لغات - الفصل الدراسي الاول
شرح كيمياء لغات اولي ثانوي - مستر احمد الباشا
كيمياء لغات - الصف الاول الثانوي - كيمياء اولي ثانوي الترم الاول - كيمستري اولي ثانوي الترم الاول