Nanotechnology (first used the term nanotechnology by
Richard Feynman, in 1959) can be defined as the manipulation of atoms and molecules at nano (one billionth) scale (1–100 nm) to produce devices, structures or systems having at least one novel or superior property. The materials having at least one dimension in the nano scale are called nanomaterials. 10-9 meter (1 nanometer) to 10-7 meter (100 nanometer)
Human eye can visualize up to 20μm only
1μm = 10-6 m

DNA= 2.5nm- 3nm Protein= ̴ 5 nm Virus= ̴ 150 nm
Human hair= ̴ 5000 nm

Properties of Nanomaterials

1. The surface area to volume ratio of the nanomaterials is relatively larger than that of bulk materials of the same mass. This increases the chemical reactivity and affects strength and electrical properties of the material.

2. The quantum confinement is observed at nanometer sizes that changes the optical, electronic and magnetic properties of the material.
The band gap increases as the size of the material is reduced to nanometer range.

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Reduction in particle size increase in its Surface area

Now, material is NANO so surface area will big… HOW?
Let us consider a sphere of radius ‘r’

Surface Area = 4 x π x r2
Volume = (4/3) x π x r3 ratio of SA to Vol = 3/r
Thus, radius of sphere decreases, Surface area will increase

Let us consider a cube of sides 1 m

Area= 6 x side2
= 6 x 1m2 = 6m2

Now, cut the same cube into 8 pieces, then the SA will increases

Area= 6 x (1/2)2 x 8 = 12m2

Similarly, the same cube into 27 pieces,

Area= 6 x (1/3)2 x 27 = 18m2

When the same volume is divided into smaller pieces, the SA increases. Hence particle size decreases and greater proportion of atom are found to surface as compared to the size.

• The combination of number of possible materials coupled with the concepts of nanochemistry is mind boggling. A few of them are:
1.

Nanoparticles of various