Nuclei

Let number of -particles and number of -particles be emitted, when uranium nucleus decays to lead nucleus. Since, -particle is doubly ionized helium atom and - particles are fast moving electrons, also mass number and atomic number remains conserved in the reaction. Equating mass number, we have Equating atomic number, we have Hence, .

Millikan oil drop method determines the charge on an electron. Liquid drop model explains nuclear fission. Shell model explains the stability of nuclei and Bohr's model accounts for the stability of the atom and the line spectra of hydrogen atom.

Nuclear radius is proportional to where, is mass number of nucleus. ie,


or
or

-particle is equivalent to helium nucleus.
The emission of an -particle from the atom of an element reduces its atomic number by , and mass number by .
Hence, the radioactive emission is as follows :
( -particle)
Also form law of conservation of momentum,

Binding energy per nucleon is maximum for . Binding energy is directly related with mass defect. Therefore, ratio of mass defect to mass number is maximum for .

A delta ray is a particle i.e., an electron, ejected from matter by ionizing radiation

Nucleones are composite particle made up of protons and neutrons. The protons and neutrons collectively present in the nucleus of an atom