Chapter 15, Problem 10TE

To determine

The explanation for late discovery of the neutron.

Answer to Problem 10TE

The existence of neutron discovered after the many years from the discovery of electron and neutron because the mass of the electron discovered later and mass of electron is not equal to the mass of proton.

Explanation of Solution

It was assumed at the time discoveries of electron and proton that the atom is made of only positive as well as negative charges only. The later discoveries show that the mass of the electrons is very small and it is not equal to the mass of the protons.

The total mass of an atom is not equal to the mass of electrons and protons, so a third particle is assumed to balance the total mass of the atom. The charge of this third atom assumed zero to maintain the atom electrically neutral.

Conclusion:

Therefore, the existence of neutron discovered after the many years from the discovery of electron and neutron because the mass of the electron discovered later and mass of electron is not equal to the mass of proton.