# Evidence of atoms

Atoms are too small. In fact, even the most powerful light-focusing microscopes can’t visualize single atoms. It is not possible actually to see the atoms but the nearest possibility to its direct evidence is by using an electron microscope.

# Using the Light Microscope:

A clear and accurate image of an object that is smaller than the | of visible light, cannot be obtained. Thus an ordinary optical (Light) microscope can measure the size of an object up to or above 500 nm (1nm = 10−9 m). So the atom is not visible in the light microscope.

# Using Electron Microscope:

The nearest possibility to direct the evidence of an atom is by using an electron microscope. However, the object of the size of the atom can be seen in the electron microscope. It uses a beam of electrons instead of visible light because the wavelength of an electron is much shorter than that of visible light.
Properties of an atom using an electron microscope:

## • Diameter of Atom:

In the 20th century, X-ray work has shown that the diameter of atoms are of the order 2×10−10 m which is 0.2 nm

## • Masses of Atom:

Masses of atoms range from 10-27 to 10-25 kg. They are often expressed in atomic mass units (amu) when 1 amu is = 1.661×10−27 kg.

## • Size of Atom:

The atom is about 10-10 meters (or 10-8 centimetres) in size. You can have an idea about the amazingly small size of an atom from the fact that a full stop may have 2 million atoms present in it.
Atoms are too small. In fact, even the most powerful light-focusing microscopes can’t visualize single atoms. It is not possible actually to see the atoms but the nearest possibility to its direct evidence is by using an electron microscope.