Question

why electron can't exist in nucleius

Answer 1

On the basis of Heisenberg's uncertainty principle, it can be shown as to why electron cannot exist within the atomic nucleus. The radius of the atomic nucleus is of the order of 10-15 m. Now, if the electron were to exist within the nucleus, then the maximum uncertainty in its position would have been 10-15 m.

Mass of electron, m = 9.1 x 10-31 kg, Dx =1 x 10-15 m.

The value of uncertainty in velocity, Dv is much higher than the velocity of light (3.0 x 108 ms-1) and therefore, it is not possible. Hence an electron cannot be found within the atomic nucleus.